Boy, it’s been a while since I even did an RPG400 program. You might try this, however. When you comile the program, specify the following parameter on the CRTRPGPGM command: OPTION(*LSTDBG). If what I am reading correctly, this stores all source information on the RPG object to allow full debug of all source in the program including copy modules.
Also if you create the program with this method you can use the ILE debug command STRDBG on it by specifying parameter OPMSRC(*YES).
At some point you might think about using CVTRPGSRC to convert your RPG programs to RPGLE. There is a lot of cool functions you are missing staying with the old RPG.
AFAIK, you can’t control /COPY access while using STRISDB. Nor should you.
Compile with OPTION( *LSTDBG ) and use STRDBG OPMSRC( *YES ). The suggestion to convert to RPG IV is even better.
There hasn’t been any enhancement to RPG II nor RPG III in this area for a decade or more. Nor has STRISDB been enhanced. Nor are any of them ever going to be enhanced. They are obsolete, and it takes less effort to convert them than to try to debug them.