On Wed, Dec 10, 2025 at 06:19:13PM -0600, Keven Hall wrote:
> If you’re intercepting a type 1, 2, or six SVC, the interrupted SVC
> number will be in the current RB otherwise for a type 3 or 4 SVC the
> interrupted SVC number will be in the previous RB.
Close.
For SVC screening the type is probably the type the screen specifies
not the type of the SVC being screened.
{It looks a bit tricky to screen different types (say type 1 & type 2)}
{with the same screen. I've never had to do that. }
Types 2,3 & 4 get a new SVRB to save the callers registers.
Types 1 and 6 don't get a SVRB so the TCBs top RB is the same as when
the SVC was issued.
Type 1 has to hold the local lock.
Type 6 has to preserve disablement (and more).
https://www.ibm.com/docs/en/zos/3.2.0?topic=routines-writing-svc
