I think we can move that to the padding that was the watchdog timer...

src/kuroko/vm.h

@@ -191,10 +191,9 @@ typedef struct KrkThreadState {
 	KrkInstance * module;      /**< The current module execution context. */
 	KrkValue currentException; /**< When an exception is thrown, it is stored here. */
 	int flags;                 /**< Thread-local VM flags; each thread inherits the low byte of the global VM flags. */
-	long _padding;             /**< Unused. */
+	KrkValue * stackMax;       /**< End of allocated stack space. */
 
 	KrkValue scratchSpace[KRK_THREAD_SCRATCH_SIZE]; /**< A place to store a few values to keep them from being prematurely GC'd. */
-	KrkValue * stackMax;
 } KrkThreadState;
 
 /**