Lib, as in ad-lib? Not encouraging.
Libby is familiar as a nn for
Elizabeth, and I find it preferable.
Liv used to be fine as a nn for
Olivia,
Olive etc, but now there's that golf tournament in Saudi Arabia called
Liv 'because' they only play 54 holes! It's nice to know that
Roman numerals still have their uses, but the politics behind the golf ... not very nice at all.