Depends: a stack is associated with each thread that the application runs: so if it only ever starts one thread - it's main thread - and doesn't do anything to start any more, then it will get one and only one stack.
That's not strictly accurate (as there is a separate stack that is used by device drivers that your app may interface with and such like) but it's accurate enough for 99.99% of applications!
The actual size of the stack is variable at build time, (See
MSDN: /F flag[
^]) and also may vary depending on the environment your app runs in. It does not change at run time.
[edit]Typo[/edit]