Salinger studied Zen Buddhism extensively, and his interest in Eastern religion, philosophy, and spirituality is reflected in Franny and Zooey. What's so interesting is that Salinger takes concepts that are relatively foreign to his fictional time and place and explores them in this context anyway – Zen meets Christianity meets a college coed. The characters in Franny and Zooey admittedly suffer from their spirituality; their heightened awareness to spiritual concerns prevents them from living a "normal" American life (of materialism and commercialism, Salinger seems to comment). Yet this suffering is necessary to lead to the wisdom or even enlightenment found at the end of the novel.
All the Glass children are trying to fight against materialism, and they all suffer for their efforts.
Franny's crisis is practical, not spiritual.