diff --git a/bin/check/check-tool.c b/bin/check/check-tool.c
index 8a1b3ac348..dd833f6c4d 100644
--- a/bin/check/check-tool.c
+++ b/bin/check/check-tool.c
@@ -106,10 +106,6 @@ add(char *key, int value) {
 	isc_result_t result;
 	isc_symvalue_t symvalue;
 
-	if (isc_g_mctx == NULL) {
-		isc_mem_create("check-tool", &isc_g_mctx);
-	}
-
 	if (symtab == NULL) {
 		isc_symtab_create(isc_g_mctx, freekey, isc_g_mctx, false,
 				  &symtab);
diff --git a/bin/check/named-checkconf.c b/bin/check/named-checkconf.c
index 0a49aec299..5485837fc9 100644
--- a/bin/check/named-checkconf.c
+++ b/bin/check/named-checkconf.c
@@ -599,15 +599,15 @@ main(int argc, char **argv) {
 		case 'm':
 			if (strcasecmp(isc_commandline_argument, "record") == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGRECORD;
+				isc_mem_debugon(ISC_MEM_DEBUGRECORD);
 			}
 			if (strcasecmp(isc_commandline_argument, "trace") == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGTRACE;
+				isc_mem_debugon(ISC_MEM_DEBUGTRACE);
 			}
 			if (strcasecmp(isc_commandline_argument, "usage") == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGUSAGE;
+				isc_mem_debugon(ISC_MEM_DEBUGUSAGE);
 			}
 			break;
 		default:
@@ -616,8 +616,6 @@ main(int argc, char **argv) {
 	}
 	isc_commandline_reset = true;
 
-	isc_mem_create("default", &isc_g_mctx);
-
 	while ((c = isc_commandline_parse(argc, argv, CMDLINE_FLAGS)) != EOF) {
 		switch (c) {
 		case 'a':
@@ -688,7 +686,6 @@ main(int argc, char **argv) {
 			}
 			FALLTHROUGH;
 		case 'h':
-			isc_mem_detach(&isc_g_mctx);
 			usage();
 
 		default:
@@ -711,7 +708,6 @@ main(int argc, char **argv) {
 	}
 
 	if (isc_commandline_index + 1 < argc) {
-		isc_mem_detach(&isc_g_mctx);
 		usage();
 	}
 	if (argv[isc_commandline_index] != NULL) {
@@ -752,9 +748,5 @@ cleanup:
 		cfg_parser_destroy(&parser);
 	}
 
-	if (isc_g_mctx != NULL) {
-		isc_mem_detach(&isc_g_mctx);
-	}
-
 	return result == ISC_R_SUCCESS ? 0 : 1;
 }
diff --git a/bin/check/named-checkzone.c b/bin/check/named-checkzone.c
index 7f90883c81..98a18ad78b 100644
--- a/bin/check/named-checkzone.c
+++ b/bin/check/named-checkzone.c
@@ -109,11 +109,6 @@ main(int argc, char **argv) {
 	FILE *errout = stdout;
 	char *endp;
 
-	/*
-	 * Uncomment the following line if memory debugging is needed:
-	 * isc_mem_debugging |= ISC_MEM_DEBUGRECORD;
-	 */
-
 	outputstyle = &dns_master_style_full;
 
 	isc_commandline_init(argc, argv);
@@ -518,7 +513,6 @@ main(int argc, char **argv) {
 		usage();
 	}
 
-	isc_mem_create("default", &isc_g_mctx);
 	if (!quiet) {
 		RUNTIME_CHECK(setup_logging(errout) == ISC_R_SUCCESS);
 	}
@@ -560,7 +554,6 @@ main(int argc, char **argv) {
 		fprintf(errout, "OK\n");
 	}
 	destroy();
-	isc_mem_detach(&isc_g_mctx);
 
 	return (result == ISC_R_SUCCESS) ? 0 : 1;
 }
diff --git a/bin/confgen/rndc-confgen.c b/bin/confgen/rndc-confgen.c
index 2b75446f9b..89ff68f398 100644
--- a/bin/confgen/rndc-confgen.c
+++ b/bin/confgen/rndc-confgen.c
@@ -145,7 +145,7 @@ main(int argc, char **argv) {
 			keyname = isc_commandline_argument;
 			break;
 		case 'M':
-			isc_mem_debugging = ISC_MEM_DEBUGTRACE;
+			isc_mem_debugon(ISC_MEM_DEBUGTRACE);
 			break;
 
 		case 'm':
@@ -218,7 +218,6 @@ main(int argc, char **argv) {
 	}
 	algname = dst_hmac_algorithm_totext(alg);
 
-	isc_mem_create("default", &isc_g_mctx);
 	isc_buffer_init(&key_txtbuffer, &key_txtsecret, sizeof(key_txtsecret));
 
 	generate_key(isc_g_mctx, alg, keysize, &key_txtbuffer);
@@ -282,7 +281,5 @@ options {\n\
 		isc_mem_stats(isc_g_mctx, stderr);
 	}
 
-	isc_mem_detach(&isc_g_mctx);
-
 	return 0;
 }
diff --git a/bin/confgen/tsig-keygen.c b/bin/confgen/tsig-keygen.c
index ed01c35c03..553a45eaf2 100644
--- a/bin/confgen/tsig-keygen.c
+++ b/bin/confgen/tsig-keygen.c
@@ -130,7 +130,7 @@ main(int argc, char **argv) {
 			}
 			break;
 		case 'M':
-			isc_mem_debugging = ISC_MEM_DEBUGTRACE;
+			isc_mem_debugon(ISC_MEM_DEBUGTRACE);
 			break;
 		case 'm':
 			show_final_mem = true;
@@ -194,8 +194,6 @@ main(int argc, char **argv) {
 	/* Use canonical algorithm name */
 	algname = dst_hmac_algorithm_totext(alg);
 
-	isc_mem_create("default", &isc_g_mctx);
-
 	if (keyname == NULL) {
 		const char *suffix = NULL;
 
@@ -278,7 +276,5 @@ nsupdate -k <keyfile>\n");
 		isc_mem_stats(isc_g_mctx, stderr);
 	}
 
-	isc_mem_detach(&isc_g_mctx);
-
 	return 0;
 }
diff --git a/bin/delv/delv.c b/bin/delv/delv.c
index 22882e289e..021aeb6dee 100644
--- a/bin/delv/delv.c
+++ b/bin/delv/delv.c
@@ -1599,8 +1599,8 @@ preparse_args(int argc, char **argv) {
 				}
 				break;
 			case 'm':
-				isc_mem_debugging = ISC_MEM_DEBUGTRACE |
-						    ISC_MEM_DEBUGRECORD;
+				isc_mem_debugon(ISC_MEM_DEBUGTRACE |
+						ISC_MEM_DEBUGRECORD);
 				break;
 			case '4':
 				if (ipv6only) {
diff --git a/bin/dig/dig.c b/bin/dig/dig.c
index 41d7a3bd28..d4dec3f116 100644
--- a/bin/dig/dig.c
+++ b/bin/dig/dig.c
@@ -2960,8 +2960,8 @@ preparse_args(int argc, char **argv) {
 				break;
 			case 'm':
 				memdebugging = true;
-				isc_mem_debugging = ISC_MEM_DEBUGTRACE |
-						    ISC_MEM_DEBUGRECORD;
+				isc_mem_debugon(ISC_MEM_DEBUGTRACE |
+						ISC_MEM_DEBUGRECORD);
 				break;
 			case 'r':
 				/*
diff --git a/bin/dig/host.c b/bin/dig/host.c
index 6df09b890c..2afcf7638d 100644
--- a/bin/dig/host.c
+++ b/bin/dig/host.c
@@ -577,15 +577,15 @@ pre_parse_args(int argc, char **argv) {
 			memdebugging = true;
 			if (strcasecmp("trace", isc_commandline_argument) == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGTRACE;
+				isc_mem_debugon(ISC_MEM_DEBUGTRACE);
 			} else if (strcasecmp("record",
 					      isc_commandline_argument) == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGRECORD;
+				isc_mem_debugon(ISC_MEM_DEBUGRECORD);
 			} else if (strcasecmp("usage",
 					      isc_commandline_argument) == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGUSAGE;
+				isc_mem_debugon(ISC_MEM_DEBUGUSAGE);
 			}
 			break;
 
diff --git a/bin/dnssec/dnssec-cds.c b/bin/dnssec/dnssec-cds.c
index 5b92267bd4..22d1852f62 100644
--- a/bin/dnssec/dnssec-cds.c
+++ b/bin/dnssec/dnssec-cds.c
@@ -1052,11 +1052,8 @@ cleanup(void) {
 		free_keytable(&new_key_tbl);
 	}
 	free_all_sets();
-	if (isc_g_mctx != NULL) {
-		if (print_mem_stats && verbose > 10) {
-			isc_mem_stats(isc_g_mctx, stdout);
-		}
-		isc_mem_detach(&isc_g_mctx);
+	if (print_mem_stats && verbose > 10) {
+		isc_mem_stats(isc_g_mctx, stdout);
 	}
 }
 
@@ -1075,8 +1072,6 @@ main(int argc, char *argv[]) {
 
 	isc_commandline_init(argc, argv);
 
-	isc_mem_create("default", &isc_g_mctx);
-
 	isc_commandline_errprint = false;
 
 #define OPTIONS "a:c:Dd:f:i:ms:T:uv:V"
@@ -1112,8 +1107,8 @@ main(int argc, char *argv[]) {
 			}
 			break;
 		case 'm':
-			isc_mem_debugging = ISC_MEM_DEBUGTRACE |
-					    ISC_MEM_DEBUGRECORD;
+			isc_mem_debugon(ISC_MEM_DEBUGTRACE |
+					ISC_MEM_DEBUGRECORD);
 			break;
 		case 's':
 			startstr = isc_commandline_argument;
diff --git a/bin/dnssec/dnssec-dsfromkey.c b/bin/dnssec/dnssec-dsfromkey.c
index cb4976cb5d..0eaf67d505 100644
--- a/bin/dnssec/dnssec-dsfromkey.c
+++ b/bin/dnssec/dnssec-dsfromkey.c
@@ -383,8 +383,6 @@ main(int argc, char **argv) {
 
 	isc_commandline_init(argc, argv);
 
-	isc_mem_create("default", &isc_g_mctx);
-
 	isc_commandline_errprint = false;
 
 #define OPTIONS "12Aa:Cc:d:Ff:K:sT:v:whV"
@@ -547,7 +545,6 @@ main(int argc, char **argv) {
 	if (verbose > 10) {
 		isc_mem_stats(isc_g_mctx, stdout);
 	}
-	isc_mem_detach(&isc_g_mctx);
 
 	fflush(stdout);
 	if (ferror(stdout)) {
diff --git a/bin/dnssec/dnssec-importkey.c b/bin/dnssec/dnssec-importkey.c
index 6a1b3768dc..31f51c01ed 100644
--- a/bin/dnssec/dnssec-importkey.c
+++ b/bin/dnssec/dnssec-importkey.c
@@ -309,8 +309,6 @@ main(int argc, char **argv) {
 
 	isc_commandline_init(argc, argv);
 
-	isc_mem_create("default", &isc_g_mctx);
-
 	isc_commandline_errprint = false;
 
 #define CMDLINE_FLAGS "D:f:hK:L:P:v:V"
@@ -454,7 +452,6 @@ main(int argc, char **argv) {
 	if (verbose > 10) {
 		isc_mem_stats(isc_g_mctx, stdout);
 	}
-	isc_mem_detach(&isc_g_mctx);
 
 	fflush(stdout);
 	if (ferror(stdout)) {
diff --git a/bin/dnssec/dnssec-keyfromlabel.c b/bin/dnssec/dnssec-keyfromlabel.c
index e4b3db6687..31a61b5bab 100644
--- a/bin/dnssec/dnssec-keyfromlabel.c
+++ b/bin/dnssec/dnssec-keyfromlabel.c
@@ -149,8 +149,6 @@ main(int argc, char **argv) {
 
 	isc_commandline_init(argc, argv);
 
-	isc_mem_create("default", &isc_g_mctx);
-
 	isc_commandline_errprint = false;
 
 #define CMDLINE_FLAGS "3A:a:Cc:D:E:Ff:GhI:i:kK:L:l:M:n:P:p:R:S:t:v:Vy"
@@ -699,7 +697,6 @@ main(int argc, char **argv) {
 		isc_mem_stats(isc_g_mctx, stdout);
 	}
 	isc_mem_free(isc_g_mctx, label);
-	isc_mem_detach(&isc_g_mctx);
 
 	if (freeit != NULL) {
 		free(freeit);
diff --git a/bin/dnssec/dnssec-keygen.c b/bin/dnssec/dnssec-keygen.c
index 910e3c2723..d52df7ec64 100644
--- a/bin/dnssec/dnssec-keygen.c
+++ b/bin/dnssec/dnssec-keygen.c
@@ -820,15 +820,15 @@ main(int argc, char **argv) {
 		case 'm':
 			if (strcasecmp(isc_commandline_argument, "record") == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGRECORD;
+				isc_mem_debugon(ISC_MEM_DEBUGRECORD);
 			}
 			if (strcasecmp(isc_commandline_argument, "trace") == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGTRACE;
+				isc_mem_debugon(ISC_MEM_DEBUGTRACE);
 			}
 			if (strcasecmp(isc_commandline_argument, "usage") == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGUSAGE;
+				isc_mem_debugon(ISC_MEM_DEBUGUSAGE);
 			}
 			break;
 		default:
@@ -837,8 +837,6 @@ main(int argc, char **argv) {
 	}
 	isc_commandline_reset = true;
 
-	isc_mem_create("default", &isc_g_mctx);
-
 	while ((ch = isc_commandline_parse(argc, argv, CMDLINE_FLAGS)) != -1) {
 		switch (ch) {
 		case '3':
@@ -1209,7 +1207,6 @@ main(int argc, char **argv) {
 	if (verbose > 10) {
 		isc_mem_stats(isc_g_mctx, stdout);
 	}
-	isc_mem_detach(&isc_g_mctx);
 
 	if (freeit != NULL) {
 		free(freeit);
diff --git a/bin/dnssec/dnssec-ksr.c b/bin/dnssec/dnssec-ksr.c
index 55e8ca9e25..8c1b059232 100644
--- a/bin/dnssec/dnssec-ksr.c
+++ b/bin/dnssec/dnssec-ksr.c
@@ -1330,8 +1330,6 @@ main(int argc, char *argv[]) {
 
 	isc_commandline_init(argc, argv);
 
-	isc_mem_create("default", &isc_g_mctx);
-
 	isc_commandline_errprint = false;
 
 #define OPTIONS "E:e:Ff:hi:K:k:l:ov:V"
diff --git a/bin/dnssec/dnssec-revoke.c b/bin/dnssec/dnssec-revoke.c
index 7708b7b759..a105f88684 100644
--- a/bin/dnssec/dnssec-revoke.c
+++ b/bin/dnssec/dnssec-revoke.c
@@ -81,8 +81,6 @@ main(int argc, char **argv) {
 		usage();
 	}
 
-	isc_mem_create("default", &isc_g_mctx);
-
 	isc_commandline_errprint = false;
 
 	while ((ch = isc_commandline_parse(argc, argv, "E:fK:rRhv:V")) != -1) {
@@ -251,7 +249,6 @@ cleanup:
 	if (dir != NULL) {
 		isc_mem_free(isc_g_mctx, dir);
 	}
-	isc_mem_detach(&isc_g_mctx);
 
 	return 0;
 }
diff --git a/bin/dnssec/dnssec-settime.c b/bin/dnssec/dnssec-settime.c
index 4a747fb0ad..312706e314 100644
--- a/bin/dnssec/dnssec-settime.c
+++ b/bin/dnssec/dnssec-settime.c
@@ -243,8 +243,6 @@ main(int argc, char **argv) {
 		usage();
 	}
 
-	isc_mem_create("default", &isc_g_mctx);
-
 	setup_logging();
 
 	isc_commandline_errprint = false;
@@ -951,7 +949,6 @@ main(int argc, char **argv) {
 		isc_mem_stats(isc_g_mctx, stdout);
 	}
 	isc_mem_free(isc_g_mctx, directory);
-	isc_mem_detach(&isc_g_mctx);
 
 	return 0;
 }
diff --git a/bin/dnssec/dnssec-signzone.c b/bin/dnssec/dnssec-signzone.c
index b3325f9aff..ff0fd055cf 100644
--- a/bin/dnssec/dnssec-signzone.c
+++ b/bin/dnssec/dnssec-signzone.c
@@ -3297,15 +3297,15 @@ main(int argc, char *argv[]) {
 		case 'm':
 			if (strcasecmp(isc_commandline_argument, "record") == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGRECORD;
+				isc_mem_debugon(ISC_MEM_DEBUGRECORD);
 			}
 			if (strcasecmp(isc_commandline_argument, "trace") == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGTRACE;
+				isc_mem_debugon(ISC_MEM_DEBUGTRACE);
 			}
 			if (strcasecmp(isc_commandline_argument, "usage") == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGUSAGE;
+				isc_mem_debugon(ISC_MEM_DEBUGUSAGE);
 			}
 			break;
 		default:
diff --git a/bin/dnssec/dnssec-verify.c b/bin/dnssec/dnssec-verify.c
index 795226e5ea..f0586f710e 100644
--- a/bin/dnssec/dnssec-verify.c
+++ b/bin/dnssec/dnssec-verify.c
@@ -184,15 +184,15 @@ main(int argc, char *argv[]) {
 		case 'm':
 			if (strcasecmp(isc_commandline_argument, "record") == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGRECORD;
+				isc_mem_debugon(ISC_MEM_DEBUGRECORD);
 			}
 			if (strcasecmp(isc_commandline_argument, "trace") == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGTRACE;
+				isc_mem_debugon(ISC_MEM_DEBUGTRACE);
 			}
 			if (strcasecmp(isc_commandline_argument, "usage") == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGUSAGE;
+				isc_mem_debugon(ISC_MEM_DEBUGUSAGE);
 			}
 			break;
 		default:
@@ -201,8 +201,6 @@ main(int argc, char *argv[]) {
 	}
 	isc_commandline_reset = true;
 
-	isc_mem_create("default", &isc_g_mctx);
-
 	isc_commandline_errprint = false;
 
 	while ((ch = isc_commandline_parse(argc, argv, CMDLINE_FLAGS)) != -1) {
@@ -332,7 +330,6 @@ main(int argc, char *argv[]) {
 	if (verbose > 10) {
 		isc_mem_stats(isc_g_mctx, stdout);
 	}
-	isc_mem_detach(&isc_g_mctx);
 
 	return result == ISC_R_SUCCESS ? 0 : 1;
 }
diff --git a/bin/named/main.c b/bin/named/main.c
index a12257f3b9..7a84828429 100644
--- a/bin/named/main.c
+++ b/bin/named/main.c
@@ -361,6 +361,8 @@ parse_int(char *arg, const char *desc) {
 	return tmp;
 }
 
+static unsigned int mem_debugging = 0;
+
 static struct flag_def {
 	const char *name;
 	unsigned int value;
@@ -860,7 +862,8 @@ parse_command_line(int argc, char *argv[]) {
 			break;
 		case 'm':
 			set_flags(isc_commandline_argument, mem_debug_flags,
-				  &isc_mem_debugging);
+				  &mem_debugging);
+			isc_mem_debugon(mem_debugging);
 			break;
 		case 'N': /* Deprecated. */
 		case 'n':
diff --git a/bin/named/server.c b/bin/named/server.c
index 8a6f00011e..771ec91cbe 100644
--- a/bin/named/server.c
+++ b/bin/named/server.c
@@ -8918,7 +8918,7 @@ apply_configuration(cfg_parser_t *configparser, cfg_obj_t *config,
 		named_g_memstatistics = cfg_obj_asboolean(obj);
 	} else {
 		named_g_memstatistics =
-			((isc_mem_debugging & ISC_MEM_DEBUGRECORD) != 0);
+			((isc_mem_debugon(0) & ISC_MEM_DEBUGRECORD) != 0);
 	}
 
 	obj = NULL;
diff --git a/bin/nsupdate/nsupdate.c b/bin/nsupdate/nsupdate.c
index 8d8d9a993f..24990effda 100644
--- a/bin/nsupdate/nsupdate.c
+++ b/bin/nsupdate/nsupdate.c
@@ -1002,8 +1002,8 @@ pre_parse_args(int argc, char **argv) {
 			debugging = true;
 			ddebugging = true;
 			memdebugging = true;
-			isc_mem_debugging = ISC_MEM_DEBUGTRACE |
-					    ISC_MEM_DEBUGRECORD;
+			isc_mem_debugon(ISC_MEM_DEBUGTRACE |
+					ISC_MEM_DEBUGRECORD);
 			break;
 
 		case '4':
diff --git a/bin/rndc/rndc.c b/bin/rndc/rndc.c
index 74526f2663..e60f96ce37 100644
--- a/bin/rndc/rndc.c
+++ b/bin/rndc/rndc.c
@@ -869,7 +869,7 @@ main(int argc, char **argv) {
 			break;
 
 		case 'M':
-			isc_mem_debugging = ISC_MEM_DEBUGTRACE;
+			isc_mem_debugon(ISC_MEM_DEBUGTRACE);
 			break;
 
 		case 'm':
diff --git a/bin/tests/system/rsabigexponent/bigkey.c b/bin/tests/system/rsabigexponent/bigkey.c
index a81efbbfb8..af09f42b77 100644
--- a/bin/tests/system/rsabigexponent/bigkey.c
+++ b/bin/tests/system/rsabigexponent/bigkey.c
@@ -104,8 +104,6 @@ main(int argc, char **argv) {
 		exit(EXIT_FAILURE);
 	}
 
-	isc_mem_create(argv[0], &isc_g_mctx);
-
 	logconfig = isc_logconfig_get();
 	isc_log_settag(logconfig, "bigkey");
 
@@ -137,7 +135,6 @@ main(int argc, char **argv) {
 	printf("%s\n", filename);
 	dst_key_free(&key);
 
-	isc_mem_detach(&isc_g_mctx);
 	return 0;
 }
 
diff --git a/bin/tests/system/wire-test.c b/bin/tests/system/wire-test.c
index 9225d23a5f..5e0f475cb4 100644
--- a/bin/tests/system/wire-test.c
+++ b/bin/tests/system/wire-test.c
@@ -120,15 +120,15 @@ main(int argc, char *argv[]) {
 		case 'm':
 			if (strcasecmp(isc_commandline_argument, "record") == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGRECORD;
+				isc_mem_debugon(ISC_MEM_DEBUGRECORD);
 			}
 			if (strcasecmp(isc_commandline_argument, "trace") == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGTRACE;
+				isc_mem_debugon(ISC_MEM_DEBUGTRACE);
 			}
 			if (strcasecmp(isc_commandline_argument, "usage") == 0)
 			{
-				isc_mem_debugging |= ISC_MEM_DEBUGUSAGE;
+				isc_mem_debugon(ISC_MEM_DEBUGUSAGE);
 			}
 			break;
 		default:
@@ -137,8 +137,6 @@ main(int argc, char *argv[]) {
 	}
 	isc_commandline_reset = true;
 
-	isc_mem_create(argv[0], &isc_g_mctx);
-
 	while ((ch = isc_commandline_parse(argc, argv, CMDLINE_FLAGS)) != -1) {
 		switch (ch) {
 		case 'b':
@@ -258,7 +256,6 @@ main(int argc, char *argv[]) {
 	if (printmemstats) {
 		isc_mem_stats(isc_g_mctx, stdout);
 	}
-	isc_mem_detach(&isc_g_mctx);
 
 	return 0;
 }
diff --git a/bin/tools/dnstap-read.c b/bin/tools/dnstap-read.c
index 4d63fce426..e226efa45b 100644
--- a/bin/tools/dnstap-read.c
+++ b/bin/tools/dnstap-read.c
@@ -55,7 +55,6 @@
 
 #include "dnstap.pb-c.h"
 
-bool memrecord = false;
 bool printmessage = false;
 bool hexmessage = false;
 bool yaml = false;
@@ -347,8 +346,7 @@ main(int argc, char *argv[]) {
 	while ((ch = isc_commandline_parse(argc, argv, "mptxy")) != -1) {
 		switch (ch) {
 		case 'm':
-			isc_mem_debugging |= ISC_MEM_DEBUGRECORD;
-			memrecord = true;
+			isc_mem_debugon(ISC_MEM_DEBUGRECORD);
 			break;
 		case 'p':
 			printmessage = true;
@@ -375,8 +373,6 @@ main(int argc, char *argv[]) {
 		fatal("no file specified");
 	}
 
-	isc_mem_create("default", &isc_g_mctx);
-
 	CHECKM(dns_dt_open(argv[0], dns_dtmode_file, isc_g_mctx, &handle),
 	       "dns_dt_openfile");
 
@@ -425,7 +421,6 @@ cleanup:
 	if (message != NULL) {
 		dns_message_detach(&message);
 	}
-	isc_mem_detach(&isc_g_mctx);
 
 	exit(rv);
 }
diff --git a/bin/tools/mdig.c b/bin/tools/mdig.c
index 2f25279ba4..68a6beefee 100644
--- a/bin/tools/mdig.c
+++ b/bin/tools/mdig.c
@@ -1818,8 +1818,8 @@ preparse_args(int argc, char **argv) {
 		while (strpbrk(option, single_dash_opts) == &option[0]) {
 			switch (option[0]) {
 			case 'm':
-				isc_mem_debugging = ISC_MEM_DEBUGTRACE |
-						    ISC_MEM_DEBUGRECORD;
+				isc_mem_debugon(ISC_MEM_DEBUGTRACE |
+						ISC_MEM_DEBUGRECORD);
 				break;
 			case '4':
 				if (ipv6only) {
diff --git a/bin/tools/named-journalprint.c b/bin/tools/named-journalprint.c
index 56f2e2afff..0678b03f10 100644
--- a/bin/tools/named-journalprint.c
+++ b/bin/tools/named-journalprint.c
@@ -91,7 +91,6 @@ main(int argc, char **argv) {
 	}
 	file = argv[0];
 
-	isc_mem_create("default", &isc_g_mctx);
 	setup_logging(stderr);
 
 	if (upgrade) {
@@ -110,6 +109,6 @@ main(int argc, char **argv) {
 			fprintf(stderr, "%s\n", isc_result_totext(result));
 		}
 	}
-	isc_mem_detach(&isc_g_mctx);
+
 	return result != ISC_R_SUCCESS ? 1 : 0;
 }
diff --git a/bin/tools/named-makejournal.c b/bin/tools/named-makejournal.c
index 8ac42856d1..c18da012e2 100644
--- a/bin/tools/named-makejournal.c
+++ b/bin/tools/named-makejournal.c
@@ -128,7 +128,7 @@ main(int argc, char **argv) {
 			usage(0);
 			break;
 		case 'm':
-			isc_mem_debugging |= ISC_MEM_DEBUGRECORD;
+			isc_mem_debugon(ISC_MEM_DEBUGRECORD);
 			break;
 		default:
 			usage(1);
@@ -151,8 +151,6 @@ main(int argc, char **argv) {
 		journal = (const char *)jbuf;
 	}
 
-	isc_mem_create("default", &isc_g_mctx);
-
 	logconfig = isc_logconfig_get();
 	isc_log_createandusechannel(
 		logconfig, "default_stderr", ISC_LOG_TOFILEDESC,
@@ -218,9 +216,5 @@ cleanup:
 		dns_db_detach(&olddb);
 	}
 
-	if (isc_g_mctx != NULL) {
-		isc_mem_detach(&isc_g_mctx);
-	}
-
 	return (result != ISC_R_SUCCESS) ? 1 : 0;
 }
diff --git a/bin/tools/named-rrchecker.c b/bin/tools/named-rrchecker.c
index ac12752aaf..99a0ba4dfa 100644
--- a/bin/tools/named-rrchecker.c
+++ b/bin/tools/named-rrchecker.c
@@ -59,9 +59,6 @@ cleanup(void) {
 		isc_lex_close(lex);
 		isc_lex_destroy(&lex);
 	}
-	if (isc_g_mctx != NULL) {
-		isc_mem_detach(&isc_g_mctx);
-	}
 }
 
 ISC_NORETURN static void
@@ -169,7 +166,6 @@ main(int argc, char *argv[]) {
 		exit(EXIT_SUCCESS);
 	}
 
-	isc_mem_create("default", &isc_g_mctx);
 	isc_lex_create(isc_g_mctx, 256, &lex);
 
 	/*
diff --git a/lib/isc/crypto.c b/lib/isc/crypto.c
index 186149d60e..9e4347794f 100644
--- a/lib/isc/crypto.c
+++ b/lib/isc/crypto.c
@@ -253,6 +253,7 @@ isc__crypto_initialize(void) {
 	uint64_t opts = OPENSSL_INIT_LOAD_CONFIG;
 
 	isc_mem_create("OpenSSL", &isc__crypto_mctx);
+	isc_mem_setdebugging(isc__crypto_mctx, 0);
 	isc_mem_setdestroycheck(isc__crypto_mctx, false);
 
 #if !defined(LIBRESSL_VERSION_NUMBER) && OPENSSL_VERSION_NUMBER >= 0x30000000L
diff --git a/lib/isc/include/isc/mem.h b/lib/isc/include/isc/mem.h
index 8a4415df44..4792ed3d6b 100644
--- a/lib/isc/include/isc/mem.h
+++ b/lib/isc/include/isc/mem.h
@@ -35,7 +35,6 @@
 #define ISC_MEM_TRACKLINES 0
 #endif /* ifndef ISC_MEM_TRACKLINES */
 
-extern unsigned int isc_mem_debugging;
 extern unsigned int isc_mem_defaultflags;
 
 /*@{*/
@@ -45,14 +44,10 @@ extern unsigned int isc_mem_defaultflags;
 #define ISC_MEM_DEBUGALL \
 	(ISC_MEM_DEBUGTRACE | ISC_MEM_DEBUGRECORD | ISC_MEM_DEBUGUSAGE)
 /*!<
- * The variable isc_mem_debugging holds a set of flags for
- * turning certain memory debugging options on or off at
- * runtime.  It is initialized to the value ISC_MEM_DEGBUGGING,
- * which is 0 by default but may be overridden at compile time.
- * The following flags can be specified:
+ * The following memory debugging options can be specified:
  *
  * \li #ISC_MEM_DEBUGTRACE
- *	Log each allocation and free to isc_lctx.
+ *	Log each allocation and free.
  *
  * \li #ISC_MEM_DEBUGRECORD
  *	Remember each allocation, and match them up on free.
@@ -61,6 +56,15 @@ extern unsigned int isc_mem_defaultflags;
  * \li #ISC_MEM_DEBUGUSAGE
  *	Every time the memory usage is greater (lower) than hi_water
  *	(lo_water) mark, print the current inuse memory.
+ *
+ * These flags are set in the static variable mem_debugging.
+ * When a new memory context is created, its debugging flags
+ * are set to the current value of mem_debugging.
+ *
+ * By default, no flags are set. This can be overridden by changing
+ * ISC_MEM_DEBUGGING in mem.c. The flags can be activated at runtime by
+ * setting environment variables (for example, "ISC_MEM_DEBUGRECORD=1")
+ * or by calling isc_mem_debugon() (see below).
  */
 /*@}*/
 
@@ -217,7 +221,6 @@ extern volatile void *isc__mem_malloc;
 #endif
 void
 isc__mem_create(const char *name, isc_mem_t **_ISC_MEM_FLARG);
-
 /*!<
  * \brief Create a memory context.
  *
@@ -225,6 +228,33 @@ isc__mem_create(const char *name, isc_mem_t **_ISC_MEM_FLARG);
  * mctxp != NULL && *mctxp == NULL */
 /*@}*/
 
+unsigned int
+isc_mem_debugon(unsigned int debugging);
+unsigned int
+isc_mem_debugoff(unsigned int debugging);
+/*!<
+ * Set or clear debugging the flags for the main memory context
+ * (isc_g_mctx), and the default debugging flags for all memory
+ * contexts yet to be created (mem_debugging).
+ *
+ * Note: These are bitwise operations. To clear the existing flags
+ * before setting new ones, use isc_mem_debugoff(ISC_MEM_DEBUGALL).
+ *
+ * Returns:
+ * \li	the previous value of the debugging flags
+ */
+
+void
+isc_mem_setdebugging(isc_mem_t *ctx, unsigned int debugging);
+/*!<
+ * Set the debugging flags for a single memory context.
+ *
+ * Note: This is an assignemnt, not a bitwise operation.
+ *
+ * Requires:
+ * \li	'ctx' valid memory context without active allocation.
+ */
+
 #if ISC_MEM_TRACE
 #define isc_mem_ref(ptr)   isc_mem__ref(ptr, __func__, __FILE__, __LINE__)
 #define isc_mem_unref(ptr) isc_mem__unref(ptr, __func__, __FILE__, __LINE__)
diff --git a/lib/isc/log.c b/lib/isc/log.c
index 5aa98f684c..d46054f434 100644
--- a/lib/isc/log.c
+++ b/lib/isc/log.c
@@ -1552,6 +1552,7 @@ isc__log_initialize(void) {
 	isc_mem_t *mctx = NULL;
 
 	isc_mem_create("log", &mctx);
+	isc_mem_setdebugging(mctx, 0);
 
 	isc__lctx = isc_mem_get(mctx, sizeof(*isc__lctx));
 	*isc__lctx = (isc_log_t){
diff --git a/lib/isc/managers.c b/lib/isc/managers.c
index 55020fdecf..a01a8bac7d 100644
--- a/lib/isc/managers.c
+++ b/lib/isc/managers.c
@@ -19,7 +19,6 @@
 
 void
 isc_managers_create(uint32_t workers) {
-	isc_mem_create("default", &isc_g_mctx);
 	isc_loopmgr_create(isc_g_mctx, workers);
 	isc_netmgr_create(isc_g_mctx);
 	isc_rwlock_setworkers(workers);
@@ -32,5 +31,4 @@ isc_managers_destroy(void) {
 	 */
 	isc_netmgr_destroy();
 	isc_loopmgr_destroy();
-	isc_mem_detach(&isc_g_mctx);
 }
diff --git a/lib/isc/mem.c b/lib/isc/mem.c
index b424b3faeb..f9e807f12b 100644
--- a/lib/isc/mem.c
+++ b/lib/isc/mem.c
@@ -35,6 +35,7 @@
 #include <isc/types.h>
 #include <isc/urcu.h>
 #include <isc/util.h>
+#include <isc/uv.h>
 
 #ifdef HAVE_LIBXML2
 #include <libxml/xmlwriter.h>
@@ -64,7 +65,8 @@
 #ifndef ISC_MEM_DEBUGGING
 #define ISC_MEM_DEBUGGING 0
 #endif /* ifndef ISC_MEM_DEBUGGING */
-unsigned int isc_mem_debugging = ISC_MEM_DEBUGGING;
+
+static unsigned int mem_debugging = ISC_MEM_DEBUGGING;
 unsigned int isc_mem_defaultflags = ISC_MEMFLAG_DEFAULT;
 
 volatile void *isc__mem_malloc = mallocx;
@@ -384,6 +386,23 @@ mem_putstats(isc_mem_t *ctx, size_t size) {
  * Private.
  */
 
+static bool
+debugging_enabled(const char *name) {
+	char env_buf[256];
+	size_t env_size = sizeof(env_buf);
+
+	int r = uv_os_getenv(name, env_buf, &env_size);
+	switch (r) {
+	case 0:
+		return true;
+	case UV_ENOENT:
+		return false;
+	default:
+		UV_RUNTIME_CHECK(uv_os_getenv, r);
+		UNREACHABLE();
+	}
+}
+
 void
 isc__mem_initialize(void) {
 /*
@@ -395,6 +414,20 @@ isc__mem_initialize(void) {
 
 	isc_mutex_init(&contextslock);
 	ISC_LIST_INIT(contexts);
+
+	if (debugging_enabled("ISC_MEM_DEBUGTRACE")) {
+		mem_debugging |= ISC_MEM_DEBUGTRACE;
+	}
+
+	if (debugging_enabled("ISC_MEM_DEBUGRECORD")) {
+		mem_debugging |= ISC_MEM_DEBUGRECORD;
+	}
+
+	if (debugging_enabled("ISC_MEM_DEBUGUSAGE")) {
+		mem_debugging |= ISC_MEM_DEBUGUSAGE;
+	}
+
+	isc_mem_create("default", &isc_g_mctx);
 }
 
 void
@@ -403,6 +436,8 @@ isc__mem_shutdown(void) {
 
 	rcu_barrier();
 
+	isc_mem_detach(&isc_g_mctx);
+
 	isc__mem_checkdestroyed();
 
 	LOCK(&contextslock);
@@ -414,6 +449,40 @@ isc__mem_shutdown(void) {
 	}
 }
 
+void
+isc_mem_setdebugging(isc_mem_t *ctx, unsigned int debugging) {
+	REQUIRE(VALID_CONTEXT(ctx));
+	REQUIRE(isc_mem_inuse(ctx) == 0);
+
+	ctx->debugging = debugging;
+}
+
+unsigned int
+isc_mem_debugon(unsigned int debugging) {
+	unsigned int old_mem_debugging = mem_debugging;
+
+	if (debugging != 0) {
+		mem_debugging |= debugging;
+
+		isc_mem_setdebugging(isc_g_mctx, mem_debugging);
+	}
+
+	return old_mem_debugging;
+}
+
+unsigned int
+isc_mem_debugoff(unsigned int debugging) {
+	unsigned int old_mem_debugging = mem_debugging;
+
+	if (debugging != 0) {
+		mem_debugging &= ~debugging;
+
+		isc_mem_setdebugging(isc_g_mctx, mem_debugging);
+	}
+
+	return old_mem_debugging;
+}
+
 static void
 mem_create(const char *name, isc_mem_t **ctxp, unsigned int debugging,
 	   unsigned int flags, unsigned int jemalloc_flags) {
@@ -845,7 +914,7 @@ isc_mem_isovermem(isc_mem_t *ctx) {
 			return false;
 		}
 
-		if ((isc_mem_debugging & ISC_MEM_DEBUGUSAGE) != 0) {
+		if ((ctx->debugging & ISC_MEM_DEBUGUSAGE) != 0) {
 			fprintf(stderr,
 				"overmem %s mctx %p inuse %zu hi_water %zu\n",
 				ctx->name, ctx, inuse, hiwater);
@@ -865,7 +934,7 @@ isc_mem_isovermem(isc_mem_t *ctx) {
 			return true;
 		}
 
-		if ((isc_mem_debugging & ISC_MEM_DEBUGUSAGE) != 0) {
+		if ((ctx->debugging & ISC_MEM_DEBUGUSAGE) != 0) {
 			fprintf(stderr,
 				"overmem %s mctx %p inuse %zu lo_water %zu\n",
 				ctx->name, ctx, inuse, lowater);
@@ -1158,7 +1227,7 @@ isc__mem_checkdestroyed(void) {
 	LOCK(&contextslock);
 	if (!ISC_LIST_EMPTY(contexts)) {
 #if ISC_MEM_TRACKLINES
-		if ((isc_mem_debugging & TRACE_OR_RECORD) != 0) {
+		if ((mem_debugging & TRACE_OR_RECORD) != 0) {
 			print_contexts(file);
 		}
 #endif /* if ISC_MEM_TRACKLINES */
@@ -1378,9 +1447,9 @@ error:
 
 void
 isc__mem_create(const char *name, isc_mem_t **mctxp FLARG) {
-	mem_create(name, mctxp, isc_mem_debugging, isc_mem_defaultflags, 0);
+	mem_create(name, mctxp, mem_debugging, isc_mem_defaultflags, 0);
 #if ISC_MEM_TRACKLINES
-	if ((isc_mem_debugging & ISC_MEM_DEBUGTRACE) != 0) {
+	if ((mem_debugging & ISC_MEM_DEBUGTRACE) != 0) {
 		fprintf(stderr, "create mctx %p func %s file %s line %u\n",
 			*mctxp, func, file, line);
 	}
diff --git a/lib/isc/thread.c b/lib/isc/thread.c
index 8bc0e94ad4..5841a467fe 100644
--- a/lib/isc/thread.c
+++ b/lib/isc/thread.c
@@ -48,7 +48,7 @@ static struct call_rcu_data *isc__thread_call_rcu_data = NULL;
 
 /*
  * We can't use isc_mem API here, because it's called too early and the
- * isc_mem_debugging flags can be changed later causing mismatch between flags
+ * memory debugging flags can be changed later causing mismatch between flags
  * used for isc_mem_get() and isc_mem_put().
  */
 
diff --git a/lib/isc/uv.c b/lib/isc/uv.c
index 59330e2d40..f0dcd51212 100644
--- a/lib/isc/uv.c
+++ b/lib/isc/uv.c
@@ -133,6 +133,7 @@ isc__uv_initialize(void) {
 #if UV_VERSION_HEX >= UV_VERSION(1, 38, 0)
 	int r;
 	isc_mem_create("uv", &isc__uv_mctx);
+	isc_mem_setdebugging(isc__uv_mctx, 0);
 	isc_mem_setdestroycheck(isc__uv_mctx, false);
 
 	r = uv_replace_allocator(isc__uv_malloc, isc__uv_realloc,
diff --git a/lib/isc/xml.c b/lib/isc/xml.c
index 664a6e8fe8..2bfd0e9457 100644
--- a/lib/isc/xml.c
+++ b/lib/isc/xml.c
@@ -53,6 +53,7 @@ isc__xml_initialize(void) {
 #ifdef HAVE_LIBXML2
 #ifndef LIBXML_HAS_DEPRECATED_MEMORY_ALLOCATION_FUNCTIONS
 	isc_mem_create("libxml2", &isc__xml_mctx);
+	isc_mem_setdebugging(isc__xml_mctx, 0);
 	isc_mem_setdestroycheck(isc__xml_mctx, false);
 
 	RUNTIME_CHECK(xmlMemSetup(isc__xml_free, isc__xml_malloc,
diff --git a/tests/bench/compress.c b/tests/bench/compress.c
index 59b8759c4d..14ac709098 100644
--- a/tests/bench/compress.c
+++ b/tests/bench/compress.c
@@ -42,9 +42,6 @@ main(void) {
 	isc_result_t result;
 	isc_buffer_t buf;
 
-	isc_mem_t *mctx = NULL;
-	isc_mem_create("test", &mctx);
-
 	static dns_fixedname_t fixedname[65536];
 	unsigned int count = 0;
 
@@ -76,14 +73,14 @@ main(void) {
 		dns_compress_t cctx;
 
 		isc_buffer_init(&buf, wire, sizeof(wire));
-		dns_compress_init(&cctx, mctx, 0);
+		dns_compress_init(&cctx, isc_g_mctx, 0);
 
 		for (unsigned int i = 0; i < count; i++) {
 			dns_name_t *name = dns_fixedname_name(&fixedname[i]);
 			result = dns_name_towire(name, &cctx, &buf);
 			if (result == ISC_R_NOSPACE) {
 				dns_compress_invalidate(&cctx);
-				dns_compress_init(&cctx, mctx, 0);
+				dns_compress_init(&cctx, isc_g_mctx, 0);
 				isc_buffer_init(&buf, wire, sizeof(wire));
 			} else {
 				CHECKRESULT(result, "dns_name_towire");
@@ -100,7 +97,5 @@ main(void) {
 
 	printf("names %u\n", count);
 
-	isc_mem_detach(&mctx);
-
 	return 0;
 }
diff --git a/tests/bench/load-names.c b/tests/bench/load-names.c
index fcf9ddf6cf..210f13ec95 100644
--- a/tests/bench/load-names.c
+++ b/tests/bench/load-names.c
@@ -422,8 +422,6 @@ main(int argc, char *argv[]) {
 
 	isc_rwlock_init(&rwl);
 
-	isc_mem_create("test", &isc_g_mctx);
-
 	if (argc != 2) {
 		fprintf(stderr,
 			"usage: load-names <filename.csv> <nthreads>\n");
@@ -493,18 +491,16 @@ main(int argc, char *argv[]) {
 		       "---------- | ---------- | ---------- |\n");
 
 		for (struct fun *fun = fun_list; fun->name != NULL; fun++) {
-			isc_mem_t *mem = NULL;
 			void *map = NULL;
 
-			isc_mem_create("test", &mem);
-			map = fun->new(mem);
+			map = fun->new(isc_g_mctx);
 
 			size_t nitems = lines / (nthreads + 1);
 
 			isc_barrier_init(&barrier, nthreads);
 
 			isc_time_t t0 = isc_time_now_hires();
-			size_t m0 = isc_mem_inuse(mem);
+			size_t m0 = isc_mem_inuse(isc_g_mctx);
 
 			for (size_t i = 0; i < nthreads; i++) {
 				threads[i] = (struct thread_s){
@@ -526,13 +522,13 @@ main(int argc, char *argv[]) {
 				d1 += threads[i].d1;
 			}
 
-			size_t m1 = isc_mem_inuse(mem);
+			size_t m1 = isc_mem_inuse(isc_g_mctx);
 
 			rcu_barrier();
 
 			isc_time_t t1 = isc_time_now_hires();
 			uint64_t d3 = isc_time_microdiff(&t1, &t0);
-			size_t m2 = isc_mem_inuse(mem);
+			size_t m2 = isc_mem_inuse(isc_g_mctx);
 
 			printf("%10s | %10zu | %10.4f | %10.4f | %10.4f | "
 			       "%10.4f | %10.4f |\n",
diff --git a/tests/bench/qp-dump.c b/tests/bench/qp-dump.c
index 1ed80fad10..7d362ec529 100644
--- a/tests/bench/qp-dump.c
+++ b/tests/bench/qp-dump.c
@@ -162,8 +162,6 @@ main(int argc, char *argv[]) {
 		exit(EXIT_SUCCESS);
 	}
 
-	isc_mem_create("test", &isc_g_mctx);
-
 	filename = argv[0];
 	result = isc_file_getsize(filename, &fileoff);
 	if (result != ISC_R_SUCCESS) {
diff --git a/tests/bench/qplookups.c b/tests/bench/qplookups.c
index 966fabf629..1c142c123b 100644
--- a/tests/bench/qplookups.c
+++ b/tests/bench/qplookups.c
@@ -197,8 +197,6 @@ main(int argc, char **argv) {
 		usage();
 	}
 
-	isc_mem_create("test", &isc_g_mctx);
-
 	dns_qp_create(isc_g_mctx, &methods, NULL, &qp);
 
 	start = isc_time_monotonic();
diff --git a/tests/bench/qpmulti.c b/tests/bench/qpmulti.c
index cf7243204b..fb5f38c961 100644
--- a/tests/bench/qpmulti.c
+++ b/tests/bench/qpmulti.c
@@ -854,8 +854,6 @@ setup_tickers(isc_mem_t *mctx) {
 
 int
 main(void) {
-	isc_mem_t *mctx = NULL;
-
 	setlinebuf(stdout);
 
 	uint32_t nloops;
@@ -868,20 +866,18 @@ main(void) {
 	}
 	INSIST(nloops > 1);
 
-	isc_mem_create("test", &mctx);
-	isc_mem_setdestroycheck(mctx, true);
+	isc_mem_setdestroycheck(isc_g_mctx, true);
 	init_logging();
-	init_items(mctx);
+	init_items(isc_g_mctx);
 
-	isc_loopmgr_create(mctx, nloops);
-	setup_tickers(mctx);
+	isc_loopmgr_create(isc_g_mctx, nloops);
+	setup_tickers(isc_g_mctx);
 	isc_loop_setup(isc_loop_main(), startup, NULL);
 	isc_loopmgr_run();
 	isc_loopmgr_destroy();
 
-	isc_mem_free(mctx, item);
+	isc_mem_free(isc_g_mctx, item);
 	isc_mem_checkdestroyed(stdout);
-	isc_mem_detach(&mctx);
 
 	return 0;
 }
diff --git a/tests/isc/mem_test.c b/tests/isc/mem_test.c
index 13d73dfc4e..a19a8ee964 100644
--- a/tests/isc/mem_test.c
+++ b/tests/isc/mem_test.c
@@ -182,7 +182,6 @@ ISC_RUN_TEST_IMPL(isc_mem_inuse) {
 	ssize_t diff;
 	void *ptr;
 
-	mctx = NULL;
 	isc_mem_create("test", &mctx);
 
 	before = isc_mem_inuse(mctx);
@@ -334,18 +333,19 @@ ISC_RUN_TEST_IMPL(isc_mem_noflags) {
 	char buf[4096], *p;
 	FILE *f;
 	void *ptr;
+	unsigned int debugging;
 
 	result = isc_stdio_open("mem.output", "w", &f);
 	assert_int_equal(result, ISC_R_SUCCESS);
 
-	isc_mem_debugging = 0;
+	debugging = isc_mem_debugoff(ISC_MEM_DEBUGALL);
 	isc_mem_create("test", &mctx);
 	ptr = isc_mem_get(mctx, 2048);
 	assert_non_null(ptr);
 	isc__mem_printactive(mctx, f);
 	isc_mem_put(mctx, ptr, 2048);
 	isc_mem_detach(&mctx);
-	isc_mem_debugging = ISC_MEM_DEBUGRECORD;
+	isc_mem_debugon(debugging);
 	isc_stdio_close(f);
 
 	memset(buf, 0, sizeof(buf));
@@ -354,7 +354,7 @@ ISC_RUN_TEST_IMPL(isc_mem_noflags) {
 	result = isc_stdio_read(buf, sizeof(buf), 1, f, NULL);
 	assert_int_equal(result, ISC_R_EOF);
 	isc_stdio_close(f);
-	isc_file_remove("mem.output");
+	// isc_file_remove("mem.output");
 
 	buf[sizeof(buf) - 1] = 0;
 
@@ -433,19 +433,22 @@ ISC_RUN_TEST_IMPL(isc_mem_traceflag) {
 	char buf[4096], *p;
 	FILE *f;
 	void *ptr;
+	unsigned int debugging;
 
 	/* redirect stderr so we can check trace output */
 	f = freopen("mem.output", "w", stderr);
 	assert_non_null(f);
 
-	isc_mem_debugging = ISC_MEM_DEBUGRECORD | ISC_MEM_DEBUGTRACE;
+	debugging = isc_mem_debugoff(ISC_MEM_DEBUGALL);
+	isc_mem_debugon(ISC_MEM_DEBUGRECORD | ISC_MEM_DEBUGTRACE);
 	isc_mem_create("test", &mctx);
 	ptr = isc_mem_get(mctx, 2048);
 	assert_non_null(ptr);
 	isc__mem_printactive(mctx, f);
 	isc_mem_put(mctx, ptr, 2048);
 	isc_mem_detach(&mctx);
-	isc_mem_debugging = ISC_MEM_DEBUGRECORD;
+	isc_mem_debugoff(ISC_MEM_DEBUGALL);
+	isc_mem_debugon(debugging);
 	isc_stdio_close(f);
 
 	memset(buf, 0, sizeof(buf));
diff --git a/tests/libtest/isc.c b/tests/libtest/isc.c
index 5ababa92ac..5b6334a64d 100644
--- a/tests/libtest/isc.c
+++ b/tests/libtest/isc.c
@@ -67,16 +67,13 @@ setup_workers(void **state ISC_ATTR_UNUSED) {
 
 int
 setup_mctx(void **state ISC_ATTR_UNUSED) {
-	isc_mem_debugging |= ISC_MEM_DEBUGRECORD;
-	isc_mem_create("test", &isc_g_mctx);
+	isc_mem_debugon(ISC_MEM_DEBUGRECORD);
 
 	return 0;
 }
 
 int
 teardown_mctx(void **state ISC_ATTR_UNUSED) {
-	isc_mem_detach(&isc_g_mctx);
-
 	return 0;
 }