Do threads have their own stack?

[John E]

Or alternatively, is the stack safe in a multithreaded app (yes, I guess it must be but here's what I'm getting at - consider the following code)

int some_func()
{
static int x;

      x = call_some_other_func();

      return x;
}

I appreciate that if the above function was getting called from 2 different threads (without any thread synchronisation) it'd be a recipe for disaster because there's only one copy of 'x' being shared between two unsynchronised threads. But what if 'x' was a local variable...?

int some_func()
{
int x;

      x = call_some_other_func();

      return x;
}

Assuming that 'call_some_other_func()' was thread safe, is it safe to call the above function from two unsynchronised threads? Does each of them see a different copy of x?