Monitoring CSM

System operators can monitor the use of CSM storage by issuing the DISPLAY CSM command. CSM messages always start with the message prefix IVT. For a complete list of messages issued by CSM, see z/OS Communications Server: SNA Messages. An application can monitor the use of CSM storage by using the SNA network monitoring NMI. See "SNA network monitoring NMI" in z/OS Communications Server: IP Programmer's Guide and Reference for more detailed information.

The following information is provided by the DISPLAY CSM command.

Amount of storage allocated to each pool
Amount of storage allocated to each user of the pool
If OWNERID=ALL, the cumulative storage allocated to each user across all pools
If the OWNERID value is not specified, the maximum amount of fixed and ECSA storage that can be allocated by CSM and current values for fixed and ECSA storage
If the OWNERID value is not specified, the highest level of fixed storage obtained since the last DISPLAY CSM command was issued without the OWNERID parameter
If the OWNERID value is not specified, the highest level of fixed storage obtained since the IPL
If the OWNERID value is not specified, the highest level of ECSA obtained since the last DISPLAY CSM command was issued without the OWNERID parameter.
If the OWNERID value is not specified, the highest level of ECSA obtained since the IPL
If the OWNERID value is not specified, the names of the CSM data spaces

The DISPLAY CSM command can be used to identify a user of the pool that is consuming inordinate amounts of storage. This could occur in situations where an application fails to free buffers that it obtained from CSM. The report of storage allocated to a user is based on the user owner_ID (OWNERID operand on the DISPLAY CSM command). CSM uses the application address space identifier (ASID) as the user OWNERID. The information by OWNERID indicates the amount of storage that must be freed by the user to enable the storage to be returned to the buffer pool.

Some messages are issued by CSM when CSM storage limits are either at a critical level (90 percent of defined limits) or exceeded. In this case, the system operator can issue the MODIFY CSM command to increase the amount of fixed or ECSA storage available for CSM. CSM storage limits can be increased or decreased without requiring a re-IPL by issuing the MODIFY CSM command.

A Display CSMUSE command is available to provide the lower level of detail regarding CSM storage usage. The Display CSMUSE command provides displays of CSM storage usage by z/OS® Communications Server components. Display of this information is intended to improve the serviceability of z/OS Communications Server and to aid in CSM storage diagnosis.

For more information about these CSM commands, see z/OS Communications Server: SNA Operation. CSM storage information is also provided to the performance monitor interface (PMI). This information is equivalent to the information provided for the summary format of the DISPLAY CSM command. See z/OS Communications Server: SNA Customization for more information.