Components of function call: (1) put arguments somewhere (2) put return address somewhere (3) jump to function.
Components of call/cc: (1) put return address as argument somewhere (2) put return address somewhere (3) jump to function.
That said, continuations generally assume that "put X somewhere" means somewhere != stack. Yes, even return addresses are not intended to be on the stack when using continuations. The main problem is when compiling down to C, which always assumes that somewhere == stack. If you're compiling down to machine language where you have access to everything, then you can just ignore the stack, but not in C, which inherently expects the stack.
