As already noted, the Atari&#x27;s banking window is outside of the stack area. IIRC, André Fachat&#x27;s Geck&#x2F;OS optionally makes use of an enhanced MMU which bank switches the stack area, but we have no such mechanism on the Atari. What I came up with is a hybrid stack segmentation&#x2F;caching approach. Even when copying is required, stack frames are typically very shallow, so the fixed stack isn&#x27;t quite as burdensome as supposed.