JDFOBJ/programs cannot be debugged with STRDBG command
The reason is because Oracle developers compiled their source code from llibrary PGFSRC91 (and others) which do not exist on your system. I believe that the object programs that Oracle ships with each release should be debuggable by us. Oracle should compile from library JDFSRC/JDESRC on their system so that command STRDBG can find the source on my system!
On your system, STRDBG will error out with the message:
File JDESRC in library PGFSRC91 with member P01051 not found.
Message ID . . . . . . : CPF9C27 Severity . . . . . . . : 40
Message type . . . . . : Diagnostic