> However, those registers are also part of the stack! This is a confusion of two kinds of stacks. There is the call stack, and the operand stack. The call sta

> However, those registers are also part of the stack! This is a confusion of two kinds of stacks. There is the call stack, and the operand stack. The call stack stores frames for executing procedures (functions) and the operand stack (if any) is used for local data flow. The operand stack, again, if any, may be nested inside of the storage of the call stack (eliminating one of two stack pointers), but need not necessarily be.