The Continuum of Care (CoC) Program is a federal program designed to promote a communitywide commitment to the goal of ending homelessness by providing funding for permanent housing, supportive services, rapid re-housing, and permanent supportive housing for homeless individuals, youth and families.
Strongholds are underground structures found in Minecraft after Beta 1.8, only three strongholds spawn per map. Most Strongholds have several Mob Spawners, an abundance of three types of Stone Brick, Stone Slabs, Cobblestone and Chests with randomized loot.
Some strongholds are not perfectly generated. There are only 3 strongholds in a world, if I remember correctly. If you found all of them and none had a library, you won't find a library at all. If you only need bookshelves I'd recommend you to find a village. The librarian has a house with a few bookshelves in it. To your question in the comment: Abandoned mineshafts are not only found at strongholds.