Slide 8

Unlike SVC screening, z/OS does not offer a service to screen Program Calls (PC). However, PCs are a z/Architecture feature that is well documented. Each address space can be assigned its own PC table but in practice, PC tables are normally shared between multiple address spaces. In most shops, there are probably no more than a handful of PC tables active at any given time. TDF exploits the z/Architecture to create a PC table that can be used to screen PCs at the address space level.

TDF currently screens ESTAEX and IEAMSCHD calls. For ESTAEX, TDF inserts system breakpoints for create, cancel, call and return.

For IEAMSCHD, TDF inserts breakpoints prior to the schedule, after the schedule, prior to the SRB being executed and after the SRB returns.

Plans are to expand PC screening to SCHEDIRB and ARR PC calls.

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