What's on the stack?

[cfry@MIT.EDU (Christopher Fry)]

I want to write a function that returns a list of the symbols
of the functions called to get to the current stack frame.
Example:

(foo (bar  (baz  (stack-calls)))) => (foo bar baz)

I imagine this can be done with a fn for getting the current stack 
frame, and functions for accessing the slots of the stack frame
for type-of-frame, fn, previous-frame.

I'd like to do this in both MCL1.3.2 and MCL 2.0