I am looking to code my first online catalog reorg in a z/OS environment and was wondering if there were any gotchas I needed to be aware of?

Thanks in advance!

As far as I know, not all the catalog/directory table spaces can be reorged in online. There are some restrictions while using them. Online reorg is not permitted for catalog and directory table spaces with links. I doubt DB2 permits REORG on these two table spaces DSNDB01.SYSUTILX and DSNDB01.SYSLGRNX.

Be sure to take a full image copy both before and after reorg of any DB2 catalog/Directory object.