.1..  ....           TCBRTM1E     "X'40'" - RTM1 IS
                                                        CURRENTLY PROCESSING
                                                        EUT FRR'S FOR THIS
                                                        TASK

If its enabled for I/O and external interrupts and didn't issue a setlock then 
the
FRR is a  EUT FRR ?

-----Original Message-----
From: IBM Mainframe Discussion List [mailto:IBM-MAIN@bama.ua.edu] On Behalf Of 
Jim Thomas
Sent: Sunday, July 17, 2011 5:22 PM
To: IBM-MAIN@bama.ua.edu
Subject: Re: Explination of EUT/FRR

ARR's are only required by PC-ss and then too, only if they're entered in 
an enabled and unlocked task mode. Don't think we had them back then, hence
FRR's. 

Aside from that, FRR's are LIFO and I believe (though I cannot remember them
of the top of my bald head) there are TCB flags that indicate their
presence.
 

Kind Regards

Jim Thomas
617-233-4130             (mobile)
636-294-1014                (res)
j...@thethomasresidence.us (Email)


-----Original Message-----
From: IBM Mainframe Discussion List [mailto:IBM-MAIN@bama.ua.edu] On Behalf
Of michealbutz
Sent: Sunday, July 17, 2011 4:00 PM
To: IBM-MAIN@bama.ua.edu
Subject: Re: Explination of EUT/FRR

Didn't realize the that color was removed when the message was sent 

Here are my questions

Thanks in Advance


FRR information is stored off of PSA - not in any task related block. 


Statement.  As opposed to a SCB Thus  the routine FRR can be  called by a
SRB or TCB since
PSA is
related to the CPU

 Question  What if there is a CPU switch in the routine being protected by
the FRR    

When DAS came out (MVS/SP1.3) ESTAE could not operate in other than
primary=home=secondary. The only way a PC routine could do recovery was thru
an FRR. Rather than require that these routines get a lock to be protected,
a
secondary FRR stack was created and a bit in PSA that indicated that an EUT
FRR stack was active. Then, if there is a task switch, the EUT FRR stack is
saved and restored upon redispatch.

Question I thought PC routines are protected by a ARR

Question  Going back to the first comment if EUT FRR are per TASK how does
the Z/OS know
they are
         the secondary since all FRR's   Are Created by SETFRR    




-----Original Message-----
From: IBM Mainframe Discussion List [mailto:IBM-MAIN@bama.ua.edu] On Behalf
Of michealbutz
Sent: Sunday, July 17, 2011 4:48 PM
To: IBM-MAIN@bama.ua.edu
Subject: Re: Explination of EUT/FRR

Questions in RED

-----Original Message-----
From: IBM Mainframe Discussion List [mailto:IBM-MAIN@bama.ua.edu] On Behalf
Of Binyamin
Dissen
Sent: Sunday, July 17, 2011 4:17 PM
To: IBM-MAIN@bama.ua.edu
Subject: Re: Explination of EUT/FRR

On Sun, 17 Jul 2011 15:45:30 -0400 michealbutz <michealb...@optonline.net>
wrote:

:>  I have seen these terms EUT Enabled Unlocked Task /FRR and this my
understanding

:>  I ASSUME Enabled means Enabled for I/O interrupts BIT 6 of Psw the only
way I know how
:>to set this is with the LPSW inst

Also External.

IOW not subjected to be interrupted by something external.

:>  Unlocked means not holding a Lock  Holding a Lock means using   some
Flavor of the
:>SetLock

:> Task means running in Task Mode as opposed to a SRB

:>  When the Term FRR is appended it means this unit of work is protected by
a FRR

More of a historical thing.

FRR information is stored off of PSA - not in any task related block. 

As opposed to a SCB Thus  the routine FRR can be  called by a SRB or TCB
since PSA is
releated to the CPU
What if there is a CPU switch in the routine being protected by the FRR    

When DAS came out (MVS/SP1.3) ESTAE could not operate in other than
primary=home=secondary. The only way a PC routine could do recovery was thru
an FRR. Rather than require that these routines get a lock to be protected,
a
secondary FRR stack was created and a bit in PSA that indicated that an EUT
FRR stack was active. Then, if there is a task switch, the EUT FRR stack is
saved and restored upon redispatch.

I thought PC routnes are protected by a ARR

Going back to the first comment if EUT FRR are per TASK how does the Z/OS
know they are
the secondary since all FRR's 
Are Created by SETFRR    

A key zero routine in any environment (TCB/SRB, any address spaces) can
define
an EUT FRR. Of course, if the routine was in TASK mode this does add
restrictions (one the EUT FRR is established no SVCs, etc.) but if the
routine
does not know how it is being called and does not need the services this is
an
easy way to go.

--
Binyamin Dissen <bdis...@dissensoftware.com>
http://www.dissensoftware.com

Director, Dissen Software, Bar & Grill - Israel


Should you use the mailblocks package and expect a response from me,
you should preauthorize the dissensoftware.com domain.

I very rarely bother responding to challenge/response systems,
especially those from irresponsible companies.

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