diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index cd613f7..94bdbba 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -63,6 +63,12 @@ int libxl_ctx_alloc(libxl_ctx **pctx, int version,
      * only as an initialiser, not as an expression. */
     memcpy(&ctx->lock, &mutex_value, sizeof(ctx->lock));
 
+    if(pthread_key_create(&ctx->tls_key, NULL) < 0) {
+        LIBXL__LOG_ERRNOVAL(ctx, LIBXL__LOG_ERROR, errno,
+            "cannot create tls key");
+        return ERROR_FAIL;
+    }
+
     if ( stat(XENSTORE_PID_FILE, &stat_buf) != 0 ) {
         LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "Is xenstore daemon running?\n"
                      "failed to stat %s", XENSTORE_PID_FILE);
diff --git a/tools/libxl/libxl_internal.c b/tools/libxl/libxl_internal.c
index 34edaf3..815021d 100644
--- a/tools/libxl/libxl_internal.c
+++ b/tools/libxl/libxl_internal.c
@@ -19,6 +19,7 @@
 #include <stdarg.h>
 #include <string.h>
 
+#include <pthread.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
@@ -70,12 +71,17 @@ void libxl__free_all(libxl__gc *gc)
     void *ptr;
     int i;
 
+    gc->nested--;
+    if (gc->nested > 0)
+        return;
+
     for (i = 0; i < gc->alloc_maxsize; i++) {
         ptr = gc->alloc_ptrs[i];
         gc->alloc_ptrs[i] = NULL;
         free(ptr);
     }
     free(gc->alloc_ptrs);
+    pthread_setspecific(CTX->tls_key, NULL);
 }
 
 void *libxl__zalloc(libxl__gc *gc, int bytes)
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index b479c49..6daa511 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -91,6 +91,8 @@ struct libxl__ctx {
     xc_interface *xch;
     struct xs_handle *xsh;
 
+    pthread_key_t tls_key;
+
     pthread_mutex_t lock; /* protects data structures hanging off the ctx */
       /* Always use CTX_LOCK and CTX_UNLOCK to manipulate this.
        *
@@ -138,9 +140,9 @@ typedef struct {
     int alloc_maxsize;
     void **alloc_ptrs;
     libxl_ctx *owner;
+    int nested;
 } libxl__gc;
 
-#define LIBXL_INIT_GC(ctx) (libxl__gc){ .alloc_maxsize = 0, .alloc_ptrs = 0, .owner = ctx }
 static inline libxl_ctx *libxl__gc_owner(libxl__gc *gc)
 {
     return gc->owner;
@@ -670,7 +672,18 @@ libxl__device_model_version_running(libxl__gc *gc, uint32_t domid);
  * as a local variable.
  */
 
-#define GC_INIT(ctx)  libxl__gc gc[1] = { LIBXL_INIT_GC(ctx) }
+#define GC_INIT(ctx) \
+    libxl__gc *gc = (libxl__gc *) pthread_getspecific(ctx->tls_key); \
+    if (gc == NULL) { \
+        gc = (libxl__gc *) alloca(sizeof(libxl__gc)); \
+        gc->alloc_maxsize = 0; \
+        gc->alloc_ptrs = 0; \
+        gc->owner = ctx; \
+        gc->nested = 1; \
+        pthread_setspecific(ctx->tls_key, gc); \
+    } else { \
+        gc->nested++; \
+    }
 #define GC_FREE       libxl__free_all(gc)
 #define CTX           libxl__gc_owner(gc)