Mark,
Your command looks just fine -- you got it right.? The error message seems simple enough, meaning about PACK my guess was wrong.?
I saw another post in this thread about COMPRESS.? It tickled a memory about a predecessor or alternative to PACK, but I started in the VM world in the early 80's, so I think it predates me.? I did a bit of checking with an old manual I have (CMS Command Reference, Rel 5), Lynn Wheeler's postings at garlic.com, and the VM Share archives at marist.edu.? I found a reference to a 'COMPRESS EXEC', (10/08/85 at 22:47 by Michael Coffin - Fidelity Systems Company) but no further leads.? Hopefully, something here will tickle another memory in the group; otherwise, reverse-engineering might be the only path left.
Jim