🚀 go-pugleaf

I've been experimenting in this area lately as well.  The IBM
documentation is found in the IMS/ESA Version 4 Application
Programming: Data Communications and Data Communications
Administration Guide manuals.

I don't have access to NS/DOS, but I have written a couple of simple
REXX execs on the mainframe that drive an IMS transaction.  Simply
because the transaction is driven by the APPC/IMS interface, it
becomes an implicit mode transaction.  In their most simple form, the
REXX execs look like (using  CPI-C terminology):

  CMALLC (to allocate a session to IMS)
  CMSEND (to send data to IMS and cause the transacton to run)
  CMRCV  (to receive data from the IMS transaction)

If the information in the manuals is insufficient or unclear, I'd
suggest opening an ASKQ record on IBMLink (if that's available to
you) to ask the particular question(s) you have in mind.

Rick Stafford
Blue Cross of R.I.