STACKS_ENTRY_SIZE
STACKS_ENTRY_SIZE(next->se_depth));
mdb_free(cur, STACKS_ENTRY_SIZE(cur->se_depth));
STACKS_ENTRY_SIZE(next->se_depth));
mdb_free(cur, STACKS_ENTRY_SIZE(cur->se_depth));
nsep = mdb_zalloc(STACKS_ENTRY_SIZE(depth), UM_SLEEP);