fix for issue 237

src/vm.c

@@ -110,6 +110,9 @@ void vmInit(void) {
     /* LZF requires a lot of stack */
     pthread_attr_init(&server.io_threads_attr);
     pthread_attr_getstacksize(&server.io_threads_attr, &stacksize);
+    if(!stacksize) {
+        stacksize = 1;
+    }
     while (stacksize < REDIS_THREAD_STACK_SIZE) stacksize *= 2;
     pthread_attr_setstacksize(&server.io_threads_attr, stacksize);
     /* Listen for events in the threaded I/O pipe */