Probably 1980s. I remember a book that was one of those story-within-a-story novels. The 'outer' story was about a girl that lived (possibly captured) in a magical tower with a spiral staircase and a magical library containing all the books in the world, including those books that hadn't been written yet. She also had a magical bear companion. Magical flowers/vines/ironwork on the cover. I think the inner story might have been the contents of one of the books, but I don't remember what it was about. Alternately the story about the girl/bear/tower might have been the inner story and I've completely forgotten the framing one.