statspack result interpretation

 Since AWR requires separate license, we are using statspack right now.

My questions is, is there a good documentation out there that gives a general guideline of how to interpret the statspack results? Such as generally, when which number crosses which threadshold will raise a red flag. I know that before oracle 8, db buffer cache hit ratio are supposed to be above 95%, but now is not the case anymore. What about library hit? This database has some objects converted from the old AS400, so these tables are generally used as read only purpse. There are other objects that are associated with transactions. I assume this make this database a hybrid.