IBM-Main would have been a better home for the post. <snip> I discovered this program </snip>
Curious: did you discover this program's loadmod installed on your system, or did you just discover the source for the program? If the former, you should alert your support staff (and likely upper management) immediately. To be completely fair, without seeing the ETDEF for this PC it is probably not knowable if this is or is not a "magic PC". If the PC were defined to give control in problem state, this might not be an exposure, depending on the PKM that was established. If entered in problem state, the SPKA would blow up unless the key of the SPKA was represented within the PKM. And if that PKM represented the caller's PKM, the caller already had the authority to do that SPKA. Now, the odds of that being why someone created this are close to 0.... <snip> Once this PC routine Branches back to the users code (BSM 0,1), the user code is running in supervisor state and would issue a PR instruction to remove the entry from the linkage stack. I find this code very messy. How would the user code return to an instruction following the BSM so the PC Service Routine would issue the PR instruction ? </snip> We should not care that it's messy; it is unacceptable code regardless. As mentioned above, it is not true that the user code is necessarily running in supervisor state (although likely). The user code's PR would do what PR does when it corresponds to a PC - removing the entry from the linkage stack and giving control to the instruction after the PC, in the PC issuer's state and key (assuming that the key 0 routine did not change the linkage stack entry itself). Peter Relson z/OS Core Technology Design
