Re: AW: Re: Fastest way to read OLDEST GDG entry

2015-11-19 Thread Paul Gilmartin 
On Wed, 18 Nov 2015 09:17:25 -0800, John Mattson wrote:
>...
>   A third possibility which is kludgy would be to create each new DS with
>a unique DATETIME in the DSN and then do the catalog list and search for
>the oldest date.  No roll-off, no problems with new GDGs coming in.
>
Alas, JCL has no facility for creating a new DS with a unique DATETIME
in the DSN.  GDGs provide this in JCL.

-- gil

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Re: AW: Re: Fastest way to read OLDEST GDG entry

2015-11-19 Thread Lizette Koehler 
Gil,
You can use the symbols for DATE and HOUR and so forth.  I think it is 
documented  z/OS 2.1.0>z/OS MVS>z/OS MVS Initialization and Tuning 
Reference>Overview>Sharing parmlib definitions>What are system symbols?>Dynamic 
system symbols

https://www-01.ibm.com/support/knowledgecenter/SSLTBW_2.1.0/com.ibm.zos.v2r1.ieae200/dynpsm.htm


New symbol  Old symbol
 

 


Lizette


> -Original Message-
> From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On
> Behalf Of Paul Gilmartin
> Sent: Thursday, November 19, 2015 10:51 AM
> To: IBM-MAIN@LISTSERV.UA.EDU
> Subject: Re: AW: Re: Fastest way to read OLDEST GDG entry
> 
> On Wed, 18 Nov 2015 09:17:25 -0800, John Mattson wrote:
> >...
> >   A third possibility which is kludgy would be to create each new DS
> >with a unique DATETIME in the DSN and then do the catalog list and
> >search for the oldest date.  No roll-off, no problems with new GDGs coming 
> >in.
> >
> Alas, JCL has no facility for creating a new DS with a unique DATETIME in the 
> DSN.
> GDGs provide this in JCL.
> 
> -- gil
> 

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Re: AW: Re: Fastest way to read OLDEST GDG entry

2015-11-19 Thread Paul Gilmartin 
On Thu, 19 Nov 2015 10:58:01 -0700, Lizette Koehler wrote:

>Gil,
>You can use the symbols for DATE and HOUR and so forth.  I think it is 
>documented  z/OS 2.1.0>z/OS MVS>z/OS MVS Initialization and Tuning 
>Reference>Overview>Sharing parmlib definitions>What are system 
>symbols?>Dynamic system symbols
>
>https://www-01.ibm.com/support/knowledgecenter/SSLTBW_2.1.0/com.ibm.zos.v2r1.ieae200/dynpsm.htm
>
>
>New symbol Old symbol
>
>   
>
>   
> 
Hmmm...  I think that's new in 2.1.  I haven't tried it.

o If two jobs are submitted close in time, is there a possibility of DSN 
conflict?
  I believe GDG would eliminate this.

o IBM contributors have acknowledged here that there's a timing window:
  if  and  are referenced close to midnight (who'd ever
  schedule a job for midnight!?) a 23 hour 59 minute error might result if
  the date changes between the two references.

  Why doesn't IBM fix that?  Rexx does it right.  JCL developers should read
  the Rexx manual to see how.

-- gil

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Re: AW: Re: Fastest way to read OLDEST GDG entry

2015-11-17 Thread Shmuel Metz (Seymour J.) 
In , on 11/17/2015
   at 03:59 PM, Peter Hunkeler  said:

> I can't tell the details from memory, but in Assembler you can code
>so that you get control when the system reaches the end of one dsn in
>the concatenation, just before it is going to open the next one.

That might work if you have the unlike attributes bit set, but since
you are only going to process one data set, why not use RDJFCB to get
the name?
 
-- 
 Shmuel (Seymour J.) Metz, SysProg and JOAT
 ISO position; see  
We don't care. We don't have to care, we're Congress.
(S877: The Shut up and Eat Your spam act of 2003)

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