As described in Sec. 11.4, there is a special handle table used to allocate IDs for processes and threads. The algorithms for handle tables normally allocate the first available handle (maintaining the free list in LIFO order). In recent releases of Windows this was changed so that the ID table always keeps the free list in FIFO order. What is the problem that the LIFO ordering potentially causes for allocating process IDs, and why does not UNIX have this problem?