Write a compiler sometime; it'll be more obvious why the term of art is "stack allocation" instead of something that doesn't include the word "allocation." You'll understand why C's "alloca" function and C#'s "stackalloc" keyword are named like that. Stack overflows will make more sense--obviously you can't allocate forever, because you are indeed allocating memory.

As a parting gift, I'll give you one guess what the title of the Wikipedia article on thread stacks is.

https://en.wikipedia.org/wiki/Stack-based_memory_allocation