diff --git a/configure.ac b/configure.ac
index 1d1d1c7fa6..a85bc0a3c7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1580,6 +1580,12 @@ test -z "$with_dlz_stub" && with_dlz_stub=no
 
 AC_CHECK_HEADERS([glob.h])
 
+#
+# Support for constructor and destructor attributes
+#
+AX_GCC_FUNC_ATTRIBUTE([constructor])
+AX_GCC_FUNC_ATTRIBUTE([destructor])
+
 #
 # Files to configure.  These are listed here because we used to
 # specify them as arguments to AC_OUTPUT.
diff --git a/lib/dns/openssl_link.c b/lib/dns/openssl_link.c
index bb26adcf26..1060fcc4ff 100644
--- a/lib/dns/openssl_link.c
+++ b/lib/dns/openssl_link.c
@@ -68,8 +68,6 @@ isc_result_t
 dst__openssl_init(const char *engine) {
 	isc_result_t result = ISC_R_SUCCESS;
 
-	isc_tls_initialize();
-
 	enable_fips_mode();
 
 #if !defined(OPENSSL_NO_ENGINE)
@@ -110,7 +108,6 @@ dst__openssl_destroy(void) {
 	}
 	e = NULL;
 #endif /* if !defined(OPENSSL_NO_ENGINE) */
-	isc_tls_destroy();
 }
 
 static isc_result_t
diff --git a/lib/isc/include/isc/tls.h b/lib/isc/include/isc/tls.h
index d0318262e5..3741f19f5e 100644
--- a/lib/isc/include/isc/tls.h
+++ b/lib/isc/include/isc/tls.h
@@ -19,12 +19,6 @@
 
 typedef struct ssl_ctx_st isc_tlsctx_t;
 
-void
-isc_tls_initialize(void);
-
-void
-isc_tls_destroy(void);
-
 void
 isc_tlsctx_free(isc_tlsctx_t **ctpx);
 /*%
diff --git a/lib/isc/include/isc/util.h b/lib/isc/include/isc/util.h
index 8941ec125e..3c8c40b679 100644
--- a/lib/isc/include/isc/util.h
+++ b/lib/isc/include/isc/util.h
@@ -48,6 +48,16 @@
 #define ISC_NONSTRING
 #endif /* __GNUC__ */
 
+#if HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR && HAVE_FUNC_ATTRIBUTE_DESTRUCTOR
+#define ISC_CONSTRUCTOR(priority) __attribute__((constructor(priority)))
+#define ISC_DESTRUCTOR(priority)  __attribute__((destructor(priority)))
+#elif WIN32
+#define ISC_CONSTRUCTOR(priority)
+#define ISC_DESTRUCTOR(priority)
+#else
+#error Either __attribute__((constructor|destructor))__ or DllMain support needed to compile BIND 9.
+#endif
+
 /*%
  * The opposite: silent warnings about stored values which are never read.
  */
diff --git a/lib/isc/lib.c b/lib/isc/lib.c
index 8bee4c21a4..dad744903d 100644
--- a/lib/isc/lib.c
+++ b/lib/isc/lib.c
@@ -13,6 +13,12 @@
 
 #include <isc/bind9.h>
 #include <isc/lib.h>
+#include <isc/mem.h>
+#include <isc/tls.h>
+#include <isc/util.h>
+
+#include "mem_p.h"
+#include "tls_p.h"
 
 /***
  *** Functions
@@ -22,3 +28,20 @@ void
 isc_lib_register(void) {
 	isc_bind9 = false;
 }
+
+void
+isc__initialize(void) ISC_CONSTRUCTOR(101);
+void
+isc__shutdown(void) ISC_DESTRUCTOR(101);
+
+void
+isc__initialize(void) {
+	isc__mem_initialize();
+	isc__tls_initialize();
+}
+
+void
+isc__shutdown(void) {
+	isc__tls_shutdown();
+	isc__mem_shutdown();
+}
diff --git a/lib/isc/mem.c b/lib/isc/mem.c
index 9f6db54823..53ea7e6e3a 100644
--- a/lib/isc/mem.c
+++ b/lib/isc/mem.c
@@ -117,7 +117,8 @@ struct stats {
 
 static ISC_LIST(isc_mem_t) contexts;
 
-static isc_once_t once = ISC_ONCE_INIT;
+static isc_once_t init_once = ISC_ONCE_INIT;
+static isc_once_t shut_once = ISC_ONCE_INIT;
 static isc_mutex_t contextslock;
 
 /*%
@@ -440,12 +441,29 @@ default_memfree(void *ptr) {
 }
 
 static void
-initialize_action(void) {
+mem_initialize(void) {
 	isc_mutex_init(&contextslock);
 	ISC_LIST_INIT(contexts);
 	totallost = 0;
 }
 
+void
+isc__mem_initialize(void) {
+	RUNTIME_CHECK(isc_once_do(&init_once, mem_initialize) == ISC_R_SUCCESS);
+}
+
+static void
+mem_shutdown(void) {
+	isc__mem_checkdestroyed();
+
+	isc_mutex_destroy(&contextslock);
+}
+
+void
+isc__mem_shutdown(void) {
+	RUNTIME_CHECK(isc_once_do(&shut_once, mem_shutdown) == ISC_R_SUCCESS);
+}
+
 static void
 mem_create(isc_mem_t **ctxp, unsigned int flags) {
 	REQUIRE(ctxp != NULL && *ctxp == NULL);
@@ -457,8 +475,6 @@ mem_create(isc_mem_t **ctxp, unsigned int flags) {
 	STATIC_ASSERT(ALIGNMENT_SIZE >= sizeof(size_info),
 		      "alignment size too small");
 
-	RUNTIME_CHECK(isc_once_do(&once, initialize_action) == ISC_R_SUCCESS);
-
 	ctx = default_memalloc(sizeof(*ctx));
 
 	*ctx = (isc_mem_t){
@@ -1458,13 +1474,20 @@ print_contexts(FILE *file) {
 }
 #endif
 
+static atomic_uintptr_t checkdestroyed = ATOMIC_VAR_INIT(0);
+
 void
 isc_mem_checkdestroyed(FILE *file) {
-#if !ISC_MEM_TRACKLINES
-	UNUSED(file);
-#endif /* if !ISC_MEM_TRACKLINES */
+	atomic_store_release(&checkdestroyed, (uintptr_t)file);
+}
 
-	RUNTIME_CHECK(isc_once_do(&once, initialize_action) == ISC_R_SUCCESS);
+void
+isc__mem_checkdestroyed(void) {
+	FILE *file = (FILE *)atomic_load_acquire(&checkdestroyed);
+
+	if (file == NULL) {
+		return;
+	}
 
 	LOCK(&contextslock);
 	if (!ISC_LIST_EMPTY(contexts)) {
@@ -1597,8 +1620,6 @@ isc_mem_renderxml(void *writer0) {
 
 	TRY0(xmlTextWriterStartElement(writer, ISC_XMLCHAR "contexts"));
 
-	RUNTIME_CHECK(isc_once_do(&once, initialize_action) == ISC_R_SUCCESS);
-
 	LOCK(&contextslock);
 	lost = totallost;
 	for (ctx = ISC_LIST_HEAD(contexts); ctx != NULL;
@@ -1739,7 +1760,6 @@ isc_mem_renderjson(void *memobj0) {
 	json_object *memobj = (json_object *)memobj0;
 
 	memset(&summary, 0, sizeof(summary));
-	RUNTIME_CHECK(isc_once_do(&once, initialize_action) == ISC_R_SUCCESS);
 
 	ctxarray = json_object_new_array();
 	CHECKMEM(ctxarray);
diff --git a/lib/isc/mem_p.h b/lib/isc/mem_p.h
index f1889c668b..dc17e06420 100644
--- a/lib/isc/mem_p.h
+++ b/lib/isc/mem_p.h
@@ -9,8 +9,11 @@
  * information regarding copyright ownership.
  */
 
-#ifndef ISC_MEM_P_H
-#define ISC_MEM_P_H
+#pragma once
+
+#include <stdio.h>
+
+#include <isc/mem.h>
 
 /*! \file */
 
@@ -21,4 +24,11 @@ isc__mem_printactive(isc_mem_t *mctx, FILE *file);
  * a single memory context.
  */
 
-#endif /* ISC_MEM_P_H */
+void
+isc__mem_checkdestroyed(void);
+
+void
+isc__mem_initialize(void);
+
+void
+isc__mem_shutdown(void);
diff --git a/lib/isc/netmgr/netmgr.c b/lib/isc/netmgr/netmgr.c
index 5ec2ea0707..eb7a23e3a4 100644
--- a/lib/isc/netmgr/netmgr.c
+++ b/lib/isc/netmgr/netmgr.c
@@ -216,8 +216,6 @@ isc_nm_start(isc_mem_t *mctx, uint32_t workers) {
 	isc__nm_winsock_initialize();
 #endif /* WIN32 */
 
-	isc_tls_initialize();
-
 	mgr = isc_mem_get(mctx, sizeof(*mgr));
 	*mgr = (isc_nm_t){ .nworkers = workers };
 
@@ -374,8 +372,6 @@ nm_destroy(isc_nm_t **mgr0) {
 		    mgr->nworkers * sizeof(isc__networker_t));
 	isc_mem_putanddetach(&mgr->mctx, mgr, sizeof(*mgr));
 
-	isc_tls_destroy();
-
 #ifdef WIN32
 	isc__nm_winsock_destroy();
 #endif /* WIN32 */
diff --git a/lib/isc/netmgr/tlsdns.c b/lib/isc/netmgr/tlsdns.c
index 90aa605232..eaa8921b15 100644
--- a/lib/isc/netmgr/tlsdns.c
+++ b/lib/isc/netmgr/tlsdns.c
@@ -398,6 +398,7 @@ isc_nm_tlsdnsconnect(isc_nm_t *mgr, isc_nmiface_t *local, isc_nmiface_t *peer,
 	REQUIRE(VALID_NM(mgr));
 	REQUIRE(local != NULL);
 	REQUIRE(peer != NULL);
+	REQUIRE(sslctx != NULL);
 
 	sa_family = peer->addr.type.sa.sa_family;
 
@@ -1656,6 +1657,16 @@ accept_connection(isc_nmsocket_t *ssock, isc_quota_t *quota) {
 	csock->tls.state = TLS_STATE_NONE;
 
 	csock->tls.ssl = SSL_new(ssock->tls.ctx);
+
+	if (csock->tls.ssl == NULL) {
+		char errbuf[256];
+		unsigned long err = ERR_get_error();
+
+		ERR_error_string_n(err, errbuf, sizeof(errbuf));
+		fprintf(stderr, "%s:SSL_new(%p) -> %s\n", __func__,
+			ssock->tls.ctx, errbuf);
+	}
+
 	RUNTIME_CHECK(csock->tls.ssl != NULL);
 
 	r = BIO_new_bio_pair(&csock->tls.ssl_wbio, TLS_BUF_SIZE,
diff --git a/lib/isc/tests/tlsdns_test.c b/lib/isc/tests/tlsdns_test.c
index 76b8974417..b7bef12cca 100644
--- a/lib/isc/tests/tlsdns_test.c
+++ b/lib/isc/tests/tlsdns_test.c
@@ -217,8 +217,13 @@ nm_setup(void **state) {
 	int tlsdns_listen_sock = -1;
 	isc_nm_t **nm = NULL;
 
-	isc_tlsctx_createserver(NULL, NULL, &tlsdns_listen_ctx);
-	isc_tlsctx_createclient(&tlsdns_connect_ctx);
+	if (isc_tlsctx_createserver(NULL, NULL, &tlsdns_listen_ctx) !=
+	    ISC_R_SUCCESS) {
+		return (-1);
+	}
+	if (isc_tlsctx_createclient(&tlsdns_connect_ctx) != ISC_R_SUCCESS) {
+		return (-1);
+	}
 
 	tlsdns_listen_addr = (isc_sockaddr_t){ .length = 0 };
 	tlsdns_listen_sock = setup_ephemeral_port(&tlsdns_listen_addr,
diff --git a/lib/isc/tls.c b/lib/isc/tls.c
index 57066a4121..cec759d924 100644
--- a/lib/isc/tls.c
+++ b/lib/isc/tls.c
@@ -24,12 +24,12 @@
 #include <isc/util.h>
 
 #include "openssl_shim.h"
+#include "tls_p.h"
 
 static isc_once_t init_once = ISC_ONCE_INIT;
 static isc_once_t shut_once = ISC_ONCE_INIT;
 static atomic_bool init_done = ATOMIC_VAR_INIT(false);
 static atomic_bool shut_done = ATOMIC_VAR_INIT(false);
-static isc_mem_t *isc__tls_mctx = NULL;
 
 #if OPENSSL_VERSION_NUMBER < 0x10100000L
 static isc_mutex_t *locks = NULL;
@@ -52,53 +52,30 @@ isc__tls_set_thread_id(CRYPTO_THREADID *id) {
 }
 #endif
 
-#if 0
-static void *
-isc__tls_malloc(size_t size, const char *file, int line) {
-	UNUSED(file);
-	UNUSED(line);
-
-	return (isc_mem_allocate(isc__tls_mctx, size));
-}
-
-static void *
-isc__tls_realloc(void *ptr, size_t size, const char *file, int line) {
-	UNUSED(file);
-	UNUSED(line);
-
-	return (isc__mem_reallocate(isc__tls_mctx, ptr, size));
-}
-
 static void
-isc__tls_free(void *ptr, const char *file, int line) {
-	UNUSED(file);
-	UNUSED(line);
-
-	if (ptr == NULL) {
-		return;
-	}
-
-	isc__mem_free(isc__tls_mctx, ptr);
-}
-#endif
-
-static void
-isc__tls_initialize(void) {
+tls_initialize(void) {
 	REQUIRE(!atomic_load(&init_done));
 
-	isc_mem_create(&isc__tls_mctx);
-	/* isc_mem_setdestroycheck(isc__tls_mctx, false); */
-
-	/* REQUIRE(CRYPTO_set_mem_functions(isc__tls_malloc, isc__tls_realloc,
-	 * isc__tls_free) == 1); */
-
 #if OPENSSL_VERSION_NUMBER >= 0x10100000L
 	RUNTIME_CHECK(OPENSSL_init_ssl(OPENSSL_INIT_ENGINE_ALL_BUILTIN |
 					       OPENSSL_INIT_LOAD_CONFIG,
 				       NULL) == 1);
 #else
 	nlocks = CRYPTO_num_locks();
-	locks = isc_mem_get(isc__tls_mctx, nlocks * sizeof(locks[0]));
+	/*
+	 * We can't use isc_mem API here, because it's called too
+	 * early and when the isc_mem_debugging flags are changed
+	 * later and ISC_MEM_DEBUGSIZE or ISC_MEM_DEBUGCTX flags are
+	 * added, neither isc_mem_put() nor isc_mem_free() can be used
+	 * to free up the memory allocated here because the flags were
+	 * not set when calling isc_mem_get() or isc_mem_allocate()
+	 * here.
+	 *
+	 * Actually, since this is a single allocation at library load
+	 * and deallocation at library unload, using the standard
+	 * allocator without the tracking is fine for this purpose.
+	 */
+	locks = calloc(nlocks, sizeof(locks[0]));
 	isc_mutexblock_init(locks, nlocks);
 	CRYPTO_set_locking_callback(isc__tls_lock_callback);
 	CRYPTO_THREADID_set_callback(isc__tls_set_thread_id);
@@ -127,20 +104,22 @@ isc__tls_initialize(void) {
 			    "seeded' message in the OpenSSL FAQ)");
 	}
 
-	atomic_compare_exchange_strong(&init_done, &(bool){ false }, true);
+	REQUIRE(atomic_compare_exchange_strong(&init_done, &(bool){ false },
+					       true));
 }
 
 void
-isc_tls_initialize(void) {
-	isc_result_t result = isc_once_do(&init_once, isc__tls_initialize);
+isc__tls_initialize(void) {
+	isc_result_t result = isc_once_do(&init_once, tls_initialize);
 	REQUIRE(result == ISC_R_SUCCESS);
 	REQUIRE(atomic_load(&init_done));
 }
 
 static void
-isc__tls_destroy(void) {
+tls_shutdown(void) {
 	REQUIRE(atomic_load(&init_done));
 	REQUIRE(!atomic_load(&shut_done));
+
 #if OPENSSL_VERSION_NUMBER < 0x10100000L
 
 	CONF_modules_unload(1);
@@ -156,24 +135,20 @@ isc__tls_destroy(void) {
 
 	CRYPTO_set_locking_callback(NULL);
 
-	/* REQUIRE(CRYPTO_set_mem_functions(OPENSSL_malloc, OPENSSL_realloc,
-	 * OPENSSL_free) == 1); */
-
 	if (locks != NULL) {
-		INSIST(isc__tls_mctx != NULL);
 		isc_mutexblock_destroy(locks, nlocks);
-		isc_mem_put(isc__tls_mctx, locks, nlocks * sizeof(locks[0]));
+		free(locks);
 		locks = NULL;
 	}
 #endif
-	isc_mem_detach(&isc__tls_mctx);
 
-	atomic_compare_exchange_strong(&shut_done, &(bool){ false }, true);
+	REQUIRE(atomic_compare_exchange_strong(&shut_done, &(bool){ false },
+					       true));
 }
 
 void
-isc_tls_destroy(void) {
-	isc_result_t result = isc_once_do(&shut_once, isc__tls_destroy);
+isc__tls_shutdown(void) {
+	isc_result_t result = isc_once_do(&shut_once, tls_shutdown);
 	REQUIRE(result == ISC_R_SUCCESS);
 	REQUIRE(atomic_load(&shut_done));
 }
@@ -198,8 +173,6 @@ isc_tlsctx_createclient(isc_tlsctx_t **ctxp) {
 
 	REQUIRE(ctxp != NULL && *ctxp == NULL);
 
-	isc_tls_initialize();
-
 	method = TLS_client_method();
 	if (method == NULL) {
 		goto ssl_error;
@@ -248,8 +221,6 @@ isc_tlsctx_createserver(const char *keyfile, const char *certfile,
 
 	REQUIRE(ctxp != NULL && *ctxp == NULL);
 
-	isc_tls_initialize();
-
 	if (ephemeral) {
 		INSIST(keyfile == NULL);
 		INSIST(certfile == NULL);
@@ -365,6 +336,7 @@ ssl_error:
 	isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL, ISC_LOGMODULE_NETMGR,
 		      ISC_LOG_ERROR, "Error initializing TLS context: %s",
 		      errbuf);
+
 	if (ctx != NULL) {
 		SSL_CTX_free(ctx);
 	}
diff --git a/lib/isc/tls_p.h b/lib/isc/tls_p.h
new file mode 100644
index 0000000000..5d44c64b93
--- /dev/null
+++ b/lib/isc/tls_p.h
@@ -0,0 +1,18 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+#pragma once
+
+void
+isc__tls_initialize(void);
+
+void
+isc__tls_shutdown(void);
diff --git a/lib/isc/win32/DLLMain.c b/lib/isc/win32/DLLMain.c
index 3acfee4f46..c649effbc2 100644
--- a/lib/isc/win32/DLLMain.c
+++ b/lib/isc/win32/DLLMain.c
@@ -12,6 +12,13 @@
 #include <stdio.h>
 #include <windows.h>
 
+#include <isc/mem.h>
+#include <isc/tls.h>
+#include <isc/util.h>
+
+#include "mem_p.h"
+#include "tls_p.h"
+
 /*
  * Called when we enter the DLL
  */
@@ -27,6 +34,8 @@ __declspec(dllexport) BOOL WINAPI
 		 * Disable DllMain() invocation on Thread creation/destruction
 		 */
 		DisableThreadLibraryCalls(hinstDLL);
+		isc__mem_initialize();
+		isc__tls_initialize();
 		break;
 
 	/*
@@ -34,6 +43,8 @@ __declspec(dllexport) BOOL WINAPI
 	 * termination or a call to FreeLibrary.
 	 */
 	case DLL_PROCESS_DETACH:
+		isc__tls_shutdown();
+		isc__mem_shutdown();
 		break;
 
 	case DLL_THREAD_ATTACH:
@@ -43,6 +54,7 @@ __declspec(dllexport) BOOL WINAPI
 		 * disabled.
 		 */
 		INSIST(0);
+		ISC_UNREACHABLE();
 		break;
 
 	default:
diff --git a/lib/isc/win32/libisc.def.in b/lib/isc/win32/libisc.def.in
index b02fb22bbb..5797632b87 100644
--- a/lib/isc/win32/libisc.def.in
+++ b/lib/isc/win32/libisc.def.in
@@ -362,6 +362,9 @@ isc_md_get_block_size
 isc_md_type_get_size
 isc_md_type_get_block_size
 isc_md
+isc__mem_checkdestroyed
+isc__mem_initialize
+isc__mem_shutdown
 isc_mem_attach
 isc_mem_checkdestroyed
 isc_mem_create
@@ -707,8 +710,8 @@ isc_timermgr_create
 isc_timermgr_createinctx
 isc_timermgr_destroy
 isc_timermgr_poke
-isc_tls_initialize
-isc_tls_destroy
+isc__tls_initialize
+isc__tls_shutdown
 isc_tlsctx_createclient
 isc_tlsctx_createserver
 isc_tlsctx_free
diff --git a/util/copyrights b/util/copyrights
index 5c0d643f4b..ee79ea4c98 100644
--- a/util/copyrights
+++ b/util/copyrights
@@ -1994,6 +1994,7 @@
 ./lib/isc/tests/uv_wrap.h			C	2020,2021
 ./lib/isc/timer.c				C	1998,1999,2000,2001,2002,2004,2005,2007,2008,2009,2011,2012,2013,2014,2015,2016,2017,2018,2019,2020,2021
 ./lib/isc/tls.c					C	2021
+./lib/isc/tls_p.h				C	2021
 ./lib/isc/tm.c					C	2014,2016,2018,2019,2020,2021
 ./lib/isc/unix/dir.c				C	1999,2000,2001,2004,2005,2007,2008,2009,2011,2012,2016,2017,2018,2019,2020,2021
 ./lib/isc/unix/errno.c				C	2016,2018,2019,2020,2021