There are numerous means of generating a guaranteed program exception, but Mr. McKown's technique of jumping to the second halfword of the relative branch is clever.
However, if you are depending on seeing an operation exception (program-interruption code 0001, or S0C1 in Z/OS-speak), there's one situation where you could be disappointed: If the program is executing on a z14 or later, and the instruction-execution-protection (IEP) facility is active and applicable, you will get a protection exception (PIC 0004). See page 3-14 of the latest PoO for details on IEP.
