Bill Fairchild from Computer Associates nee Uccel talked about his effort in getting IOS to accept STARTIO macros. STARTIO is an IOS service that is used by many components of MVS to do I/O. Some of these are EXCP itself, VSAM, VTAM and JES3.
There was actual working code distributed at the session, which helped us to understand the technique. Unfortunately, his code was full of other bugs, and there was no shortage of uncharitable miscreants to point this out to him. The whole situation degenerated rapidly into a lively discussion of Local Locks, SYSEVENTs, SRBs and all kinds of groovy stuff and a good time was had by all until the moderator stepped in and got us back on track again.