Re: Explanation about the SVCASF bit ("SVC can be assisted") in the SVC table?

[Dori Polotsky]

Thank you both for the historical perspective, and special thanks to Jim
for the additional up-to-date clarification - it now makes much more sense.

Best regards,
 Dori


On Wed, Apr 4, 2018 at 8:44 PM, Jim Mulder  wrote:

>   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  wrote on
> 04/04/2018 11:33:07 AM:
>
> > From: Rob Scott 
> > To: IBM-MAIN@LISTSERV.UA.EDU
> > 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 
> >
> > "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:IBM-MAIN@LISTSERV.UA.EDU
> > ] On Behalf Of Dori Polotsky
> > Sent: Wednesday, April 4, 2018 10:18 AM
> > To: IBM-MAIN@LISTSERV.UA.EDU
> > 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
>
>
>
> --
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> send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
>



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Dori Polotsky
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Re: Explanation about the SVCASF bit ("SVC can be assisted") in the SVC table?

[Jim Mulder]

  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  wrote on 
04/04/2018 11:33:07 AM:

> From: Rob Scott 
> To: IBM-MAIN@LISTSERV.UA.EDU
> 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 
> 
> "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:IBM-MAIN@LISTSERV.UA.EDU
> ] On Behalf Of Dori Polotsky
> Sent: Wednesday, April 4, 2018 10:18 AM
> To: IBM-MAIN@LISTSERV.UA.EDU
> 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



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Re: Explanation about the SVCASF bit ("SVC can be assisted") in the SVC table?

[Rob Scott]

"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:IBM-MAIN@LISTSERV.UA.EDU] On Behalf 
Of Dori Polotsky
Sent: Wednesday, April 4, 2018 10:18 AM
To: IBM-MAIN@LISTSERV.UA.EDU
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

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Explanation about the SVCASF bit ("SVC can be assisted") in the SVC table?

[Dori Polotsky]

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

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