Initialization commands

Commands in the initialization input data sets are processed when WebSphere MQ is initialized on queue manager startup. Three types of command can be issued from the initialization input data sets:

• Commands to define WebSphere MQ entities that cannot be recovered (DEFINE BUFFPOOL and DEFINE PSID for example).

  These commands must reside in the data set identified by the DDname CSQINP1. They are processed before the restart phase of initialization. They cannot be issued through the console, operations and control panels, or an application program. The responses to these commands are written to the sequential data set that you refer to in the CSQOUT1 statement of the started task procedure.

• Commands to define WebSphere MQ objects that are recoverable after restart. These definitions must be specified in the data set identified by the DDname CSQINP2. They are stored in page set zero. CSQINP2 is processed after the restart phase of initialization. The responses to these commands are written to the sequential data set that you refer to in the CSQOUT2 statement of the started task procedure.

• Commands to manipulate WebSphere MQ objects. These commands must also be specified in the data set identified by the DDname CSQINP2. For example, the WebSphere MQ-supplied sample contains an ALTER QMGR command to specify a dead-letter queue for the subsystem. The response to these commands is written to the CSQOUT2 output data set.

Note:

If WebSphere MQ objects are defined in CSQINP2, WebSphere MQ attempts to redefine them each time the queue manager is started. If the queues already exist, the attempt to define them fails. If we need to define your objects in CSQINP2, we can avoid this problem by using the REPLACE parameter of the DEFINE commands, however, this will override any changes that were made during the previous run of the queue manager.

Sample initialization data set members are supplied with WebSphere MQ for z/OS. They are described in Sample definitions supplied with WebSphere MQ.

 

Initialization commands for distributed queuing

We can also use the CSQINP2 initialization data set for the START CHINIT command. If we need a series of other commands to define your distributed queuing environment (for example, starting listeners), WebSphere MQ provides a third initialization input data set, called CSQINPX, that is processed as part of the channel initiator started task procedure.

The MQSC commands contained in the data set are executed at the end of channel initiator initialization, and output is written to the data set specified by the CSQOUTX DD statement. You might use the CSQINPX initialization data set to start listeners for example.

A sample channel initiator initialization data set member is supplied with WebSphere MQ for z/OS. It is described in Sample definitions supplied with WebSphere MQ.