Checkpoint File (CKPT)

The Checkpoint file is a VSAM KSDS that contains checkpoint information generated by the DTF during execution of a copy operation. The Checkpoint file consists of variable length records, one per Process that has checkpointing specified. The average record length is 312 bytes. The equivalent of one cylinder of space is allocated during the installation. The size of the Checkpoint file can be influenced by the number of days you retain checkpoint information according to the initialization parameter, CKPT.DAYS.

From Connect:Direct z/OS 6.4 release, the length of the checkpoint file (CKPT) key has been increased from 80 to 100 bytes. As a result, the CKPT file must be redefined with updated attributes. While the maximum record length remains unchanged, the average record length increases by 56 bytes. For more details, see Upgrading IBM Connect:Direct for reference on how to define a new CKPT file.

The Instance Identifier for the Unix server has been included in the checkpoint (CKPT) file record. A valid Instance Identifier will be present only for Copy Process/Run Task initiated from the Connect:Direct Unix server to the Connect:Direct z/OS server. This Instance Identifier will also be utilized during the CKPT restart of these specific processes or tasks. Transfers from other systems will not include the Instance Identifier, and it will not be applicable in those cases.