Sure, It's limited to using a maximum of 2GB of memory if I recall correctly, as far as I'm aware it's mainly due to the 32 bit pointers that are used along with the garbage collector.

With lua I always assume people are talking about downward limitations not upward.

Yes, that is a good point, I'm planning on using lua though on a wide range of hardware ranging from MCUs through to Servers.

Is that because they're using one of the 32 bits as a boolean to mark if it should be collected? Just curious.