IBM has a small technote about it here:
It states that...
..."*NOLIBRARY is a general name given to those objects that do not have a
library address. The size of *NOLIBRARY is determined by the number of
unassigned objects in *NOLIBRARY. *NOLIBRARY is not a real library and
cannot be used as one.
Not to be confused with *NOLIB.
IBM Certified Systems Expert — eServer i5 iSeries