IMS DB: CHKP(basic, symbolic), XRST calls

Here is a way to implement checkpoint logic in IMS DB. The DLI calls CHKP and XRST are needed to implement it

Checkpoint DLI calls in IMS DB

CHKP (basic)

CHKP (basic) call’s purpose is to recover the data. It collects the checkpoint-id and writes it to the checkpoint file. When the checkpoint arrives, it commits all the work and updates the checkpoint file. This will work with both MPP and BMP. Here’s a logic to use CHKP call [techdocs.broad.com]

XRST Call

XRST call. It must be the first call. It should only be used with CHKP(symbolic) calls. It should be preceded by CHKP(symbolic) call. This is allowed in BMP and Batch applications. This call has the capability to retrieve the data stored by the CHKP(symbolic) call. Here is a way to use XRST call [docs.bmc.com]

CHKP(Symbolic)

CHKP(Symbolic) call will be used to store seven areas of the program. When the checkpoint arrives, it commits the work and updates the checkpoint file. It works with the XRST call. It is allowed in Batch and BMP applications. Here’s the usage of CHKP symbolic call [IBM.com]

References

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