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Porting to Channels and Containers


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yugendran

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Joined: 14 Dec 2007
Posts: 51
Location: indore

PostPosted: Thu Nov 12, 2015 1:02 pm
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Hi Guys,

We are trying to change to channels and containers from DFHCOMMAREA. Most of our existing code is AMODE(24). will it work, if we simply change the existing link and xctl commands to use channels to pass data. If yes, is there any performance considerations related to AMODE(24) programs to use channels?

Right now, we plan to change it as (single channel / multiple containers for a trans) as a replacement for COMMAREA.

Or is it wise to use multiple channels ie. channels for each functionality within a transaction?

I have looked at the best practices for the migration. But need to know if we should expect any issues during migration? anyone performed such activity before, plz let me know if factors to be considered?

Thanks,
Yuge
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Garry Carroll

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Joined: 08 May 2006
Posts: 1099
Location: Dublin, Ireland

PostPosted: Thu Nov 12, 2015 2:16 pm
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Quote:
Most of our existing code is AMODE(24). will it work, if we simply change the existing link and xctl commands to use channels to pass data.


Is there a reason why, when you recompile your programs to make this change, that the programs will remain AMODE(24)? These days, most languages will compile to AMODE(31) and linkedit/bind as RMODE(ANY).

The choice of whether to use single channel/single container or single channel/multiple container would depend on application design.

Garry.
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Rohit Umarjikar

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Joined: 21 Sep 2010
Posts: 2567
Location: NYC,USA

PostPosted: Thu Nov 12, 2015 11:26 pm
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I havn't seen anything other than AMODE 31, RMODE ANY, after CICS TS 3.1 so there is no question upon AMODE(24) as channels and containers are for passing the huge data with AMODE(24) you may run short-on-storage issues. And the whole purpose of channels and containers defeats.
However, I strongly advise you get used to with migration guide as all the questions you asked would be answered here along with many other interesting stuff about channels.
www.redbooks.ibm.com/redbooks/pdfs/sg247294.pdf
I advise not to make it too complex about multiple channels in pseudoconversational programming where it is tough call to evaluate which is the current channel.
Designing Consideration for Channels:
www-01.ibm.com/support/knowledgecenter/#!/SSGMCP_5.3.0/com.ibm.cics.ts.applicationprogramming.doc/topics/dfhp3_ch_overview.html?cp=SSGMCP_5.3.0%2F12-7-11
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Bill O'Boyle

CICS Moderator


Joined: 14 Jan 2008
Posts: 2504
Location: Atlanta, Georgia, USA

PostPosted: Fri Nov 13, 2015 1:00 am
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A heads-up for you regarding Channels/Containers. Since CICS/TS 3.2, they are stored "above the bar" in 64-Bit storage defined to the MEMLIMIT during Startup. Keep in mind that although they're stored in 64-Bit storage, when an application requires access, the Channel/Container is processed in your 31-Bit EUDSA (ask your CICS SYSPROG), so ensure that they're not too big. In fact, IBM warns customers about large Channels/Containers and region degradation, with SOS possibilities. Your CICS SYSPROG will probably have to increase the EDSALIMIT in the SIT.

HTH....
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