Control-Stack Format

The control stack contains only Lisp objects. Every object pointed to by an entry on this stack is kept alive.

The control stack does not have a rigid frame structure. The compiler is allowed a large amount of freedom in the use of the stack so that it choose the best calling sequences. Mostly the compiler is the only system that cares how the stack is laid out, so this isn't a big problem. See chapter for a description of the structures which allow the debugger to parse the stack.