OBJ_TAG_BITS
set_freeobj(zspage, link->next >> OBJ_TAG_BITS);
link->next = get_freeobj(zspage) << OBJ_TAG_BITS;
link->next = freeobj++ << OBJ_TAG_BITS;
link->next = freeobj++ << OBJ_TAG_BITS;
link->next = -1UL << OBJ_TAG_BITS;