I had several users whose jobs would end abnormally after about three hours of work because the Process Access Group (PAG) would grow beyond the 4MG limit. I was finally able to track down the problem.

A programmer used the FREE op code to close down an RPG program, removing the program from memory but not closing the open data paths (ODPs) for the files. The program with the FREE op code was called many times; each time it opened new ODPs over the same files. After about three hours, the PAG was so full of ODPs that the job ended abnormally. Taking FREE out and setting on *INLR solved the problem.