What controls how many values can be unpacked?

[Sam Roberts <vieuxtech@...>]

Experimentally, it appears to be 2048, but is this adjustable, a
compile time option, variable depending on environment?

> function T(i) local t={} for _=1,i do t[_] = _ end return t end
> for i=1,5000 do print(i); unpack(T(i)) end
...
2047
2048
stdin:1: stack overflow (table too big to unpack)
stack traceback:
        [C]: in function 'unpack'
        stdin:1: in main chunk
        [C]: ?

Cheers,
Sam