Overview of the space monitoring features

These problems include running out of space because all extents are full or not enough space is available on the volume to allow the data set to allocate another extent. They also include performance problems that can occur because of fragmentation, control interval (CI) splits, and control area (CA) splits.

To set up (register) a database data set for space monitoring, you can use the ISPF interface or a batch program (PCPSPACE). The setup process creates an SM PDX record for each registered database. The key of the SM record contains the IMSID and DBD name of the database to monitor.

To capture space usage statistics for a database after it is set up for monitoring, you simply execute the pointer checking process. Or you can execute PCPSPACE to collect space usage statistics without checking pointers. PCP collects space usage information about the database data sets from the DASD volume table of contents (VTOCs) and VSAM catalog entries.

PCPSPACE can also monitor the volumes on which monitored data sets reside. Volume monitoring determines whether each volume has enough space to accommodate growth of the data sets to their space thresholds. If the volume does not have enough free space available, PCPSPACE notifies you of the exception condition. Since all databases registered for monitoring must be examined to obtain volume information, volume monitoring can only be performed by PCPSPACE. The pointer checking process cannot perform volume monitoring, even though it can perform space usage and database monitoring.

PCP stores the captured statistics in the PDX data set as extensions of the SM record for the database. It stores the volume statistics as a VS member in the PDX. It can also write the space monitoring and volume monitoring reports to the SYSPRINT data set.

You can view the formatted space statistics through the PCP ISPF interface. You can also view a history of the space statistics as they change over time. This process is called trend analysis.