[lmm]

> is there a situation where there's automatic storage but no stack?

Yes. As a trivial example, some C interpreters use a different datastructure instead of a stack.

[winReInstall]

But the stack refers to the number of calling functions, stacked upon one another too? This is why its always stack, disregard the structure.. cause its a mirror of the program running, and the usual c program uses functions.

[lmm]

Well, the term is overloaded. C has recursion so an implementation needs something like a call stack, but you don't have to store it in a stack datastructure.