MQ_ALIGNSIZE
assert((_p) != 0 && !((uintptr_t)(_p) & (MQ_ALIGNSIZE -1)) && \
temp = (mqhp->mq_maxsz + MQ_ALIGNSIZE - 1) & ~(MQ_ALIGNSIZE - 1);
temp = (msgsize + MQ_ALIGNSIZE - 1) & ~(MQ_ALIGNSIZE - 1);