START CHANNEL

Use the MQSC command START CHANNEL to start a channel.


Use MQSC commands

For information on how we use MQSC commands, see Performing local administration tasks using MQSC commands.

We can issue this command from sources CR. For an explanation of the source symbols, see Sources from which we can issue MQSC commands on z/OS .

Synonym: STA CHL


START CHANNEL

START CHANNEL ( channel-name ) CMDSCOPE(' ')CMDSCOPE(qmgr-name)1CMDSCOPE(*)12CHLDISP(DEFAULT)CHLDISP(PRIVATE)CHLDISP(SHARED)1CHLDISP(FIXSHARED)12IGNSTATE(NO)(YES)3Notes:

  • 1 Valid only on z/OS when the queue manager is a member of a queue sharing group.
  • 2 Valid only on z/OS.
  • 3 Not valid on z/OS


Usage notes

  1. On z/OS, the command server and the channel initiator must be running.
  2. This command can be issued to a channel of any type except CLNTCONN channels (including those that have been defined automatically). If, however, it is issued to a receiver (RCVR), server-connection (SVRCONN) or cluster-receiver (CLUSRCVR) channel, the only action is to enable the channel, not to start it.
  3. Where there is both a locally defined channel and an auto-defined cluster-sender channel of the same name, the command applies to the locally defined channel. If there is no locally defined channel but more than one auto-defined cluster-sender channel, the command applies to the channel that was last added to the local queue manager's repository.


Parameter descriptions for START CHANNEL

    (channel-name)
    The name of the channel definition to be started. This is required for all channel types. The name must be that of an existing channel.

    CHLDISP
    This parameter applies to z/OS only and can take the values of:

    • DEFAULT
    • PRIVATE
    • SHARED
    • FIXSHARED

    If this parameter is omitted, then the DEFAULT value applies. This is taken from the default channel disposition attribute, DEFCDISP, of the channel object.

    In conjunction with the various values of the CMDSCOPE parameter, this parameter controls two types of channel:

      SHARED
      A receiving channel is shared if it was started in response to an inbound transmission directed to the queue sharing group.

      A sending channel is shared if its transmission queue has a disposition of SHARED.

      PRIVATE
      A receiving channel is private if it was started in response to an inbound transmission directed to the queue manager.

      A sending channel is private if its transmission queue has a disposition other than SHARED.

    Note: This disposition is not related to the disposition set by the disposition of the queue sharing group of the channel definition. The combination of the CHLDISP and CMDSCOPE parameters also controls from which queue manager the channel is operated. The possible options are:

    • On the local queue manager where the command is issued.
    • On another specific named queue manager in the group.
    • On every active queue manager in the group.
    • On the most suitable queue manager in the group, determined automatically by the queue manager itself.

    The various combinations of CHLDISP and CMDSCOPE are summarized in the following table:

    CHLDISP CMDSCOPE( ) or CMDSCOPE (local-qmgr) CMDSCOPE (qmgr-name) CMDSCOPE(*)
    PRIVATE Start as a private channel on the local queue manager Start as a private channel on the named queue manager Start as a private channel on all active queue managers
    SHARED For a shared SDR, RQSTR, and SVR channel, start as a shared channel on the most suitable queue manager in the group.

    For a shared RCVR and SVRCONN channel, start the channel as a shared channel on all active queue managers.

    For a shared CLUSSDR or CLUSRCVR channel, this option is not permitted.

    This might automatically generate a command using CMDSCOPE and send it to the appropriate queue managers. If there is no definition for the channel on the queue managers to which the command is sent, or if the definition is unsuitable for the command, the action fails there.

    The definition of a channel on the queue manager where the command is entered might be used to determine the target queue manager where the command is actually run. Therefore, it is important that channel definitions are consistent. Inconsistent channel definitions might result in unexpected command behavior.

    		Not permitted Not permitted
    FIXSHARED For a shared SDR, RQSTR, and SVR channel, with a nonblank CONNAME, start as a shared channel on the local queue manager.

    For all other types, this option is not permitted.    		 For a shared SDR, RQSTR, and SVR with a nonblank CONNAME, start as a shared channel on the named queue manager.

    For all other types, this option is not permitted.    		 Not permitted

    Channels started with CHLDISP(FIXSHARED) are tied to the specific queue manager; if the channel initiator on that queue manager stops for any reason, the channels are not recovered by another queue manager in the group. For more information about SHARED and FIXSHARED channels, see Starting a shared channel.

    CMDSCOPE
    This parameter applies to z/OS only and specifies how the command runs when the queue manager is a member of a queue sharing group. If CHLDISP is set to SHARED, CMDSCOPE must be blank or the local queue manager.

      ' '
      The command runs on the queue manager on which it was entered. This is the default value.

      qmgr-name
      The command runs on the queue manager you specify, providing the queue manager is active within the queue sharing group.

      We can specify a queue manager name only if we are using a queue sharing group environment and if the command server is enabled.

      *
      The command runs on the local queue manager and is also passed to every active queue manager in the queue sharing group. The effect of this is the same as entering the command on every queue manager in the queue sharing group.

      This option is not permitted if CHLDISP is FIXSHARED.

    IGNSTATE
    This parameter allows you to specify whether we want the command to return an error return code, if the object is already in the state the command would move it to. Possible values are:

      NO
      If the channel being started is already in that state, the command returns RC=10. This is the existing behavior, and NO is the default value.

      YES
      If the channel being started is already in that state, the command returns RC=0. The return code is the case as if the channel is not running.

Parent topic: MQSC commands