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Possibilities to control maximum instances of a Queue Manager Channels (RCVR)

  • 1.  Possibilities to control maximum instances of a Queue Manager Channels (RCVR)

    Posted Wed October 22, 2025 11:26 AM

    Hello everyone!


    We are looking for possibilities to control the maximum instances of a Queue Manager Channels (RCVR) on our site.

    Is there someone how have already struggled with that?


    Thanks.



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    PNR Betrieb
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  • 2.  RE: Possibilities to control maximum instances of a Queue Manager Channels (RCVR)

    Posted Thu October 23, 2025 02:49 AM

    I must admit that we only ever had problems with the amount of SVRCONN channels from the clients.
    And there we used MAXINST and MAXINSTC , only working for that type.

    Unfortunately the Qmgr values of ACTCHL, MAXCHL and TCPCHL have a Channel Initiator scope , not listener scope.
    (see reference https://www.ibm.com/docs/en/ibm-mq/9.4.x?topic=reference-alter-qmgr-alter-queue-manager-settings )

    If the parameters were listener scope you could have bound the qmgr-to-qmgr channels to a separate listener but that is not the case.



    ------------------------------
    Norbert Pfister
    system engineer
    Nuremberg
    Germany
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    Original Message


  • 3.  RE: Possibilities to control maximum instances of a Queue Manager Channels (RCVR)

    Posted Thu October 23, 2025 03:09 AM
    Edited by PNR Betrieb Thu October 23, 2025 03:17 AM

    Thank You for this information!


    Just for clarification. We are using Linux not z/OS.



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    PNR Betrieb
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    Original Message


  • 4.  RE: Possibilities to control maximum instances of a Queue Manager Channels (RCVR)

    Posted Thu October 23, 2025 07:03 PM
    Edited by Roger Lacroix Thu October 23, 2025 07:49 PM

    Nevermind



  • 5.  RE: Possibilities to control maximum instances of a Queue Manager Channels (RCVR)

    Posted Thu October 23, 2025 07:23 PM

    What symptom, problem, issue are you seeing?  

    Display chstatus of your superfluous receiver channel instances, post results here.



    ------------------------------
    bruce2359
    Consultant/trainer
    CTTECH - Computer & Telecommunications Technology
    West Coast, almost
    000-000-0000
    ------------------------------

    Original Message


  • 6.  RE: Possibilities to control maximum instances of a Queue Manager Channels (RCVR)

    Posted Fri October 24, 2025 12:13 AM

    It is possible for a Sender Channel to start over the same connection more instances just using another Queue Manager Name and we are looking for a possibility to set a maximum amount of them for each Channel Name.



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    PNR Betrieb
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    Original Message


  • 7.  RE: Possibilities to control maximum instances of a Queue Manager Channels (RCVR)

    Posted Fri October 24, 2025 01:00 AM

    Hi PNR,

    Have a read of this blog post: Avoiding run-away numbers of channels

    where it addresses this.

    Cheers,
    Morag



    ------------------------------
    Morag Hughson
    MQ Technical Education Specialist
    MQGem Software Limited
    Website: https://www.mqgem.com
    ------------------------------

    Original Message


  • 8.  RE: Possibilities to control maximum instances of a Queue Manager Channels (RCVR)

    Posted Fri October 24, 2025 03:19 AM

    Hi Morag,

    thank You for this Link!

    Unfortunately, this is not exact the same what we are looking for. We need something like "MAXINST" but also for Channel Type "RCVR".



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    PNR Betrieb
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    Original Message


  • 9.  RE: Possibilities to control maximum instances of a Queue Manager Channels (RCVR)
    Best Answer

    Posted Fri October 24, 2025 03:39 AM

    That attribut does not exist, so that's why the technique described in that blog post is your best bet. Alternatively, you could write a channel exit I suppose.

    Cheers,

    Morag



    ------------------------------
    Morag Hughson
    MQ Technical Education Specialist
    MQGem Software Limited
    Website: https://www.mqgem.com
    ------------------------------

    Original Message


  • 10.  RE: Possibilities to control maximum instances of a Queue Manager Channels (RCVR)

    Posted Fri October 24, 2025 08:38 AM

    Please also remember that there is a qm.ini stanza that would allow you to double the number of sender channel instances (from 1 to 2, has to do with performance)

    So you need to take that into consideration. On the other hand if you want to restrict the number of allowed receiver channel, as kill unauthorized access from an unknown IP, you should look into the chlauth set up for that channel where you can specify the qmgr name and the ip the connection has to originate from. Don't forget, as Morag would say, to add a backstop rule to prevent any non authorized connection.

    Hope it helps.



    ------------------------------
    Francois Brandelik
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    Original Message


  • 11.  RE: Possibilities to control maximum instances of a Queue Manager Channels (RCVR)

    Posted Fri October 24, 2025 09:06 AM

    Do the unneeded (extra) RCVR channels have similar channel names?  The qmgr SYSTEM.AUTO.RECEIVER is used to automatically create a matching rcvr channel when a sender channel attempts to start AND no matching receiver channel exists. 

    I'd suggest enabling channel events to help identify the cause.
    To enable IBM MQ channel events, use the ALTER QMGR MQSC command with CHLEV(ENABLED). You can also enable other specific channel events, such as auto-definition events, by setting their respective queue manager attributes (e.g., CHADEV(ENABLED))



    ------------------------------
    bruce2359
    Consultant/trainer
    CTTECH - Computer & Telecommunications Technology
    West Coast, almost
    000-000-0000
    ------------------------------

    Original Message


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