SVC Assist has not been used since MVS/ESA SP3.1.0 (30 years ago), so the SVCASF bit has had no meaning for 30 years. It is on in the SVC 13 and SVC 26 entries because of some obsolete code in IEAVNPS5, which should have been deleted. However, this causes no harm, since the bit is not used for anything.
Jim Mulder z/OS Diagnosis, Design, Development, Test IBM Corp. Poughkeepsie NY IBM Mainframe Discussion List <[email protected]> wrote on 04/04/2018 11:33:07 AM: > From: Rob Scott <[email protected]> > To: [email protected] > Date: 04/04/2018 12:36 PM > Subject: Re: Explanation about the SVCASF bit ("SVC can be > assisted") in the SVC table? > Sent by: IBM Mainframe Discussion List <[email protected]> > > "SVC Assist" is a facility that performed some common housekeeping > operations on behalf of the SVC - for example, copying the information > stored at the last SVC interruption into the current request block, > saving general registers, and loading the general registers with > appropriate values. > > It was implemented by opcode x'E503'. > > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected] > ] On Behalf Of Dori Polotsky > Sent: Wednesday, April 4, 2018 10:18 AM > To: [email protected] > Subject: Explanation about the SVCASF bit ("SVC can be assisted") in > the SVC table? > > Hello, > > Does anyone know the meaning of the SVCASF bit (x'01') of the SVCTP > byte of the SVC table? > > If I am not mistaken, on our system (z/OS 2.2 ADCD) following the > IPL this bit is off for all SVC's except SVC 13 (ABEND, IEAVTRT2) > and SVC 26 (LOCATE / CATALOG, IGG026DU). Also, I did not see an > option to select the value for this bit with SVCUPDTE. > > Any insights would be appreciated. > > Thank you very much, > Dori ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
