luaD_checkstack
luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
luaD_checkstack(L, p->maxstacksize); /* check again for new 'base' */
luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
luaD_checkstack(L, p->maxstacksize);
#define incr_top(L) {L->top++; luaD_checkstack(L,0);}
luaD_checkstack(L, 2); /* fmt + item */
luaD_checkstack(L, 1);
Protect(luaD_checkstack(L, n));