Tom,

Peter Abel authored a book called, Programming Assembler Language (not to be confused with his book for PC Assembler) that covers what you are looking to do.? The book is primarily oriented towards DOS/VS but has a few MVS topics.

There is a chapter called "Subprograms and Overlays" that addresses what you are attempting to perform.? It discusses the usage of R13 and save areas as well as the linkage editor statements necessary.?

I have the 2nd edition that was published in 1984, the first edition was published in 1979.

Regards,

Gary?