int
do_listen(stab, arglast)
STAB *stab;
int *arglast;
{
    register STR **st = stack->ary_array;
    register int sp = arglast[1];
    register STIO *stio;
    int backlog;

    if (!stab)
	goto nuts;

    stio = stab_io(stab);
    if (!stio || !stio->ifp)
	goto nuts;

    backlog = (int)str_gnum(st[++sp]);
    return listen(fileno(stio->ifp), backlog) >= 0;

nuts:
    if (dowarn)
	warn("listen() on closed fd");
    errno = EBADF;
    return FALSE;
}