... or a very garbled version of the story that the original IEFBR14 didn't clear R15 and so, 'completed' with a non-zero return-code ...
It's said that two APARs have been accepted against IEFBR14: 1) Non RC=0 problem 2) Not link-edited as reentrant so not available as candidate for LPA Quite an impressive record for four bytes of code!
