luaZ_resizebuffer
luaZ_resizebuffer(ls->L, ls->buff, LUA_MINBUFFER); /* initialize buffer */
luaZ_resizebuffer(ls->L, b, newsize);
luaZ_resizebuffer(L, buff, n);
#define luaZ_freebuffer(L, buff) luaZ_resizebuffer(L, buff, 0)