Whoa, thanks for your suggestions!! it supports recursion now, basically for each script function I store:
-information about its local data(local variables and function parameters), how many local vars, how many bytes needed for those local vars.
-its instructions....
-its return type

then when the script calls a function, it will:
-allocate bytes needed for the function's local data + request storage for return value
-point the function to the allocated bytes
-'push' to the call stack (make it the current function)
-execute its instructions

upon returning, it will:
-store any return value it has to store
-release all data it has
-restore call stack or 'pop'

and it worked nicely, I've tested it by making a factorial function inside the script.....now I only need to 'FIX' the stack size (I want to allocate some bytes at the beginning that acts as a stack 'pool', but that's not hard to do)

many many thanks guys !!