When the basic direct access method (BDAM) is used to process a data set, processing resumes normally upon restart. However, you must ensure that a particular block is read or written before a checkpoint is taken. Your program must complete the BDAM I/O operation by executing the CHECK or WAIT macro before it executes the CHKPT macro.

Any change made to a record between a checkpoint and a restart will remain in the data set. You are responsible for backing out any changes that would otherwise produce invalid results. For more information, see Preserving Data Set Contents. If the program does not complete the operation, the block may be read or written either before or after the checkpoint is taken.

For serially reusable resources, your program must also issue either the WRITE or RELEX macro to release a record that is read with exclusive control, before executing the CHKPT macro.