EXCESS
blk = malloc(size + EXCESS);
def.avail_out = size + EXCESS;
if (ret == Z_STREAM_END && def.avail_out >= EXCESS) {
have = size + EXCESS - def.avail_out;
tmp = malloc(size + EXCESS);
inf.avail_in = size + EXCESS;
def.avail_out = size + EXCESS;