Checkpoint records

To reduce restart time, WebSphere MQ takes periodic checkpoints during normal operation. These occur as follows:

• When a predefined number of log records has been written. This number is defined by the checkpoint frequency operand called LOGLOAD of the system parameter macro CSQ6SYSP, described in the WebSphere MQ for z/OS System Setup Guide.

• At the end of a successful restart.

• At normal termination.

• Whenever WebSphere MQ switches to the next active log data set in the cycle.

At the time a checkpoint is taken, WebSphere MQ issues the DISPLAY CONN command (described in the WebSphere MQ Script (MQSC) Command Reference) internally so that a list of connections currently in doubt is written to the z/OS console log.