VMS Help CMS, SET, NOLIBRARY, Description  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    The SET NOLIBRARY command removes one or more libraries from
    the current library search list. None of the directories in the
    library search list can be your current default directory. If all
    libraries are removed from the list, the logical name CMS$LIB is
    deassigned.