The word ***repertoire***, with its other variant ***repertory***, did once have the meaning of an ***inventory***. [Etymonline][1] explains:
> 1550s, "***an index, list, catalogue***," from Late Latin *repertorium* "***inventory, list***," from Latin *repertus*, past participle of *reperire* "to find, get, invent," from *re-*, here perhaps an intensive prefix, *+ parire*, archaic form of *paerere* "produce, bring forth" (from PIE root *pere- (1) "to produce, procure").

So there is a connotation of *all the items of a collection*, which was preserved in the specific meaning with which it is used today (performances).

For libraries, however, if you want to refer to the amount itself, better use ***collection***

> an accumulation of objects gathered for study, comparison, or exhibition or as a hobby ([M-W][2])

In fact, *library* is listed as the synonym of collection.

If you refer to the list that contains all the names of the book, *catalogue* is the best term.

> a complete list of items, typically one in alphabetical or other systematic order. ([OxfordL][3])


  [1]: https://www.etymonline.com/search?q=repertoire&ref=searchbar_searchhint
  [2]: https://www.merriam-webster.com/dictionary/collection
  [3]: https://www.google.com/search?q=catalogue%20meaning&sxsrf=ALiCzsZBSEJUMc6TgQ4JIFo5JsE8GegOMQ%3A1660048615189&ei=51TyYuT_CtG_gQbNiqvoBg&oq=catalogu&gs_lcp=Cgdnd3Mtd2l6EAEYADIJCCMQJxBGEPkBMgcIABCxAxBDMgUIABCRAjIFCAAQkQIyBQgAEJECMgQIABBDMgUIABCABDIFCAAQsQMyBQgAEIAEMgUIABCABDoHCAAQRxCwAzoHCAAQsAMQQzoHCCMQsQIQJzoGCAAQHhAHOgsIABCxAxCDARCRAjoHCAAQgAQQCjoECCMQJzoKCAAQsQMQgwEQQzoLCC4QgAQQsQMQ1AI6CwguEIAEEMcBEK8BOhEILhCABBCxAxCDARDHARCvAUoECEEYAEoECEYYAFCuB1injANg46ADaAJwAXgAgAGwAYgBtg-SAQQyLjEzmAEAoAEByAEKwAEB&sclient=gws-wiz