Also remember that EXPORT tapes are tracked in the VOLHIST file.
If you want to prevent overwriting those, you have to keep the VOLHIST
entries around.

I purge all the STGNEW, STGREUSE, and STGDELETE entries that are old than 6
months.  The only reason I keep anything THAT old, is because sometimes if a
tape turns up missing I like to be able to see when there was last a record
of it in VOLHIST.