Aren't there other ways for a stack overflow to occur, not only through recursion?
Sure. Just keep calling methods, without ever returning. You'll need a lot of methods, though, unless you allow recursion. Actually, it doesn't make a difference: a stack frame is a stack frame, whether it is one of a recursive method or not is the same.
The answer to your second question is: The stackoverflow is detected when the JVM tries to allocate the stack frame for the next call, and finds it is not possible. So, nothing will be overwritten.
