The Channels stanza on IBM i
The Channels stanza contains information about the channels.
- MaxChannels= 100|number
- The maximum number of current channels allowed. For z/OS®, the value must be 1 - 9999, with a default value of 200. For all other platforms, the default value is 999 999 999, which means the number of channels is unlimited.
- MaxActiveChannels= MaxChannels_value
- The maximum number of channels allowed to be active at any time. The default is the value specified on the MaxChannels attribute.
- MaxInitiators= 3|number
- The maximum number of initiators. The default and maximum value is 3.
- MQIBINDTYPE=FASTPATH|STANDARD
- The binding for applications.
- FASTPATH
- Channels connect using MQCONNX FASTPATH. That is, there is no agent process.
- STANDARD
- Channels connect using STANDARD.
- ThreadedListener= NO|YES
- Whether to start RUNMQLSR ( YES ) or AMQCLMAA ( NO ) as a listener.
If you specify ThreadedListener=YES, all channels run as threads of a single job. This limits the number of connections to the resources available to a single job.
If you specify ThreadedListener=NO, the non-threaded listener (AMQCLMAA) starts a new responder job (AMQCRSTA) for each inbound TCP/IP channel. The disadvantage of this technique is that it is not as fast to start a new AMQCRSTA job as it is to start a thread within a RUNMQLSR job, therefore connection times for a non-threaded listener are slower than those for a threaded listener.
- AdoptNewMCA= NO |SVR|SNDR|RCVR|CLUSRCVR|ALL|FASTPATH
- If IBM MQ receives a request to start a channel, but finds that an amqcrsta process exists for the same channel, the existing process must be stopped before the new one can start. The AdoptNewMCA attribute allows you to control the ending of an existing process and the startup of a new one for a specified channel type. If you specify the AdoptNewMCA attribute for a given channel type, but the new channel fails to start because the channel is already running:
- The new channel tries to end the previous one.
- If the previous channel server does not end by the time the AdoptNewMCATimeout wait interval expires, the process (or the thread) for the previous channel server is ended.
- If the previous channel server has not ended after step 2, and after the AdoptNewMCATimeout wait interval expires for a second time, IBM MQ ends the channel with a CHANNEL IN USE error.
You specify one or more values, separated by commas or blanks, from the following list:
- NO
- The AdoptNewMCA feature is not required. This is the default.
- SVR
- Adopt server channels
- SNDR
- Adopt sender channels
- RCVR
- Adopt receiver channels
- CLUSRCVR
- Adopt cluster receiver channels
- ALL
- Adopt all channel types, except for FASTPATH channels
- FASTPATH
- Adopt the channel if it is a FASTPATH channel. This happens only if the appropriate channel type is also specified, for example, AdoptNewMCA=RCVR,SVR,FASTPATH Attention!: The AdoptNewMCA attribute can behave in an unpredictable fashion with FASTPATH channels because of the internal design of the queue manager. Exercise great caution when enabling the AdoptNewMCA attribute for FASTPATH channels.
- AdoptNewMCATimeout= 60|1-3600
- The amount of time, in seconds, that the new process waits for the old process to end. Specify a value, in seconds, in the range 1 - 3600. The default value is 60.
- AdoptNewMCACheck=QM|ADDRESS|NAME|ALL
- The AdoptNewMCACheck attribute allows you to specify the type checking required when enabling the AdoptNewMCA attribute. It is important for you to perform all three of the following checks, if possible, to protect your channels from being shut down, inadvertently or maliciously. At the very least check that the channel names match.
Specify one or more values, separated by commas or blanks, from the following:
- QM
- The listener process checks that the queue manager names match.
- ADDRESS
- The listener process checks the communications address, for example, the TCP/IP address.
- NAME
- The listener process checks that the channel names match.
- ALL
- The listener process checks for matching queue manager names, the communications address, and for matching channel names.
The default is AdoptNewMCACheck=NAME,ADDRESS,QM.