Is it allowed to modify stack values as long as the stack stays balanced?

Question

Everybody knows it is good programming practice to keep the stack balanced. What I\'m wondering, though, is whether I\'m allowed to modify stack values in a C function called fr

Answer 1

The stack values are the property of the C function being called. You can do whatever you wish with them. The only effect to the outside is the values returned by the function.

C functions called from Lua do not need to keep the stack balanced, that is, with the same contents or number of items it had on entry.