Not enough data to answer :) Still a try:
In the best case, we need to pass a parameter to a function and we need to save the return address. Assuming sizeof (int) takes word size, this would mean, 2 words. And in factorial (N) there will be N-1 recursive calls so for say N = 76, surely there will be stack overflow.
But to realize how stupid my explanation is and also the question, please see here:
http://www.tenouk.com/Bufferoverflowc/Bufferoverflow2a.html
