is it possible to access the call stack in code?

What I mean is, if I write a subroutine into an Add-In (so that it can be
seperately secured from the rest of the code, for reasons I wish we didn't
need to deal with)

When I call a subroutine in that protected Add-In, is it possible to return,
in the code, the name of the calling routine?

It should be the next item up in the call stack.

Thanks.
Mark