[jhgb]

You can't take an address of pretty much any input parameter, return value, or local variable of a function on a stack machine because they're all on the stack CPU core's hardware data stack which has no addresses for its elements. In C you should be able to take the address of these objects, using an ampersand. That's not making an assumption?

[cryptonector]

If it's addressable memory, you can address it. That does not assume a stack however. You don't get to assume that they are in some order, not if you want your code to be portable. On typical architectures that do use a stack, if you're very careful, you do get to use the addresses of automatics to figure out whether the stack grows up or down, but that's not specifically something in standard C.