nCurrentSize = _msize(__onexitbegin);
   [b]if((nCurrentSize+sizeof(_PVFV)) < ULONG(((const BYTE*)__onexitend-
      (const BYTE*)__onexitbegin)))[b]
   {
        //...
   }

        if ( _msize_crt(__onexitbegin)
                < ((unsigned)((char *)__onexitend -
            (char *)__onexitbegin) + sizeof(_PVFV)) )
        {
            /*
             * not enough room, try to grow the table
             */
            //...
        }