There are several things that could be eating up your disk space. You have journals, performance data, etc. You can go to GO PERFORM to see how many days of performance data you are saving, the library is normally QMPGDATA. Also for journal receivers….wrkobj *all/*all *jrnrcv or for jounals….wrkobj *all/*all *jrn. Not sure if you have the system set to manage the journals, if so, how many days do have retention set to?
If you’re looking at systems where libraries are only taking 5% of the disk capacity, you’re probably looking at systems that are primarily using the directory structures of the IFS. Cleaning up “libraries” will not do much good at all on those systems.
First, you can’t rely on PRTDSKINF unless you run RTVDSKINF in order to retrieve the disk information before printing it. If you don’t run RTVDSKINF, then PRTDSKINF is probably printing old, obsolete data.
But beyond that, you would also want to run RTVDIRINF to collect details about directories. Then run PRTDIRINF to print the directory info that you collected. But be prepared — a directory report on a large system can be extremely large.