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Checkpoint file

LMS requires that a VSAM KSDS checkpoint file be available to every operating system image. This file contains the information needed to support the 14-day grace period. The checkpoint file is managed locally by each system that uses it. It is allocated automatically, if does not already exist, by the CMSC and records are added and deleted automatically. The contents of this file do not require any further editingOne checkpoint file can be used for any number of operating system images, and for any number of LMS subsystems on these images. Or you can define a different file for each image and/or subsystem. The DASD on which the checkpoint file resides must be available to LMS at all times, starting LMS being run under the CMSC throughout the life of the system IPL. This data set is accessed by only the CMSC and by LMS exit programs that are invoked by the operating system whenever a CPU Upgrade on Demand or an LPAR defined capacity change occurs.

Using LMS client parameters to define the checkpoint data set

Use the following parameters to define the checkpoint data set—only CHKPT_DSNAME is required.

  •  CHKPT_DSNAME
  •  CHKPT_VOLSER
  •  CHKPT_STORCLASS
  •  CHKPT_MGMTCLASS
  •  CHKPT_DATACLASS

Checkpoint data set security

You must ensure that the checkpoint data set is appropriately protected by your installation’s security system (RACF, ACF/2, and CA-Top Secret).

Because the CMSC and the exit programs that create and update the checkpoint data set are APF-authorized routines, they must issue their own calls to the Security Access Facility (SAF) interface to ensure that the user ID under which they are running has the appropriate access to create and/or update the checkpoint data set. The user ID under which the CMSC runs must have ACCESS=ALTER if the checkpoint data set does not exist, and it must have ACCESS=CONTROL if the data set already exists.

The system exits run under the user ID of the last LMS execution that ran for the subsystem in question.

 Sharing the checkpoint data set

The LMS checkpoint data set is protected by a QNAME/RNAME combination where QNAME is CPWRCKPT and RNAME is the 1-38 character data set name itself. If you are sharing one checkpoint data set among multiple systems then this QNAME/RNAME combination must be eligible for cross-system sharing.

The ENQ for this QNAME/RNAME is issued with SCOPE=SYSTEMS. Therefore you may have to adjust your GRS RNL (or the MIM equivalent) parameters to support sharing of these names multiple operating systems.

If you have disabled this GRS function for your installation, then you MUST NOT SHARE your checkpoint data sets.

Important

Although the checkpoint data set may be shared among multiple LPARS which are running BMC AMI products, the restriction exists that the LMS version must be the same.


 

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