+#include <thread.h>
+#ifdef LISP_FEATURE_STACK_GROWS_DOWNWARD_NOT_UPWARD
+#define CONTROL_STACK_GUARD_PAGE(th) ((void *)(th->control_stack_start))
+#else
+#define CONTROL_STACK_GUARD_PAGE(th) \
+ (((void *)(th->control_stack_end)) - os_vm_page_size)
+#endif
+