To allow an automatic step restart or an automatic checkpoint/restart, you must observe the following rules when preparing the job used in the original execution:

1. If a step restart is desired, the RD parameter must be coded to request the restart.
2. If a checkpoint/restart is desired, a DD statement for the checkpoint data set must be included in the step that executes the CHKPT macro instruction.
3. The EXEC statements in the job must have unique names. (Upon restart, the system searches for the named step.)
4. If commands are in the original job, the commands are not reexecuted when restart occurs.
5. The DD statement VOL=REF parameter is ignored if restart is attempted from a checkpoint taken when the DD statements are opened out of order and the referenced DD statement requested nonspecific tape volumes.
6. When using passed data sets, the same temporary data set name should not be reused after the temporary data set has been deleted.
7. If the checkpoint data set is SMS-managed, the automatic class selection (ACS) routine must not override the unit or volume selection.