The JES2 checkpoint reconfiguration is entered for a number of reasons. JES2 can initiate a reconfiguration to correct an I/O error, ask the operator to validate checkpoint data set forwarding information, or move the checkpoint off a volatile coupling facility structure. Also, you can initiate a reconfiguration dialog whenever needed with a $T CKPTDEF,RECONFIG=YES command. The dialog is then both a means to correct a problem situation and a way to maintain the coupling facility and DASD. If problems occur during a reconfiguration, JES2 provides a number of diagnostic messages to assist your understanding of the error condition.