This encompasses both spawning a process into a permanent region and switching between tasks; the former is probably the more difficult, since Forth compiles statefully and incrementally.

One solution might be to force the program to declare its size ahead-of-time, and adjust https://git.sr.ht/~remexre/stahl/tree/10b2e606/src/kernel-aarch64/forth/builtins.s#L105 to compensate?