if your outer function f called a function 'quicksort' which called a function 'partition' which called your nested function 'compare', how did 'compare' get access to the variables of f from its statically enclosing scope? how did it know how many locals 'quicksort' and 'partition' had pushed onto the operand stack?
well, that's the problem the static link solves; it's not such a difficult thing to implement if you let procedure values (function pointers) be two words instead of one. gcc emits trampoline code onto the stack at runtime to support this without breaking abi compatibility, so the pointer to the nested function actually points to the trampoline, which just supplies the static link and calls the real nested function
