MODIFY CSM command
MODIFY CSM command to update CSM storage value or to activate CSM PARMLIB member values: >>-MODIFY-- --procname--,--CSM--+---------------------+--+---------------------+--+-------------------------+->< '-,--ECSA--=--maxecsa-' '-,--FIXED--=--maxfix-' '-,--HVCOMM--=--maxhvcomm-'
Abbreviations
| Operand | Abbreviation |
|---|---|
| MODIFY | F |
Purpose
MODIFY CSM command to update CSM storage value or to activate CSM PARMLIB member values:
The MODIFY CSM command is used to dynamically change the
amount of storage used by the communications storage manager (CSM).
It can also be used to activate changes made to the CSM parmlib member
without requiring an IPL.
- To temporarily change the amount of storage used by CSM, issue this command and specify the parameters that you want to change on the ECSA, HVCOMM, and FIXED operands.
- To permanently change the amount of storage used by CSM or tuning parameters for CSM buffer pools, edit the CSM parmlib member and issue this command without specifying any operands.
Note: Changing a parameter that decreases the specification
of a limit may not take effect immediately. Reducing the usage of
the resource to comply to the new limit may require users to free
buffers to contract a storage pool's size. This type of change could
also result in a CSM constraint condition being indicated to users
that are monitoring CSM resource usage.
For more information about the CSM parmlib member, see the z/OS Communications Server: New Function Summary.
MODIFY CSM command to activate or deactivate CSM Buffer Monitoring or request the dynamic CSM Buffer Monitoring:
Using the Modify CSM command, the operator can start or stop dynamic CSM buffer monitoring. For more information about CSM Monitoring, see z/OS Communications Server: New Function Summary.
Operands
- procname
- The procedure name for the command. If procname in the START command was specified as startname.ident, where startname is the VTAM® start
procedure and ident is the optional identifier,
either startname.ident or ident can be specified for procname.
If procname in the START command was startname, startname must be specified for procname.
- ECSA=maxecsa
- Specifies the maximum number of bytes of extended common system
area (ECSA) storage to be dedicated for use by CSM. The maxecsa value is a decimal integer; specify the value
in either kilobytes (K) or megabytes (M) ranging from 1024K-2048M. Guideline: The maxecsa value should be less than 90% of the ECSA available on the z/OS® system. CSM adjusts the maxecsa value to 90% of the system ECSA value and issues message IVT5590I when the maxecsa value is greater than 90% of the ECSA available on the system.
- FIXED=maxfix
- Specifies the maximum number of bytes of fixed storage to be dedicated for use by CSM. maxfix is a decimal integer and must be specified in either kilobytes (K) or megabytes (M) ranging from 1024K to 30720M.
- Guideline: CSM ECSA and CSM data space can be requested to be fixed. z/OS ensures the real frame that is backing the storage matches the CSM data space type of request. For example: CSM DSPACE64 buffers are backed with a real frame that is above the 2G line.
- HVCOMM=maxhvcomm
- Specifies the maximum number of bytes of 64-bit high virtual common (HVCOMM) storage to be dedicated for use by CSM. maxhvcomm is a decimal integer and must be specified in megabytes (M) ranging from 100M to 999999M.
- MONITOR=YES
- Specifies that CSM Buffer Monitoring will be activated. It provides the component IDs of the users of CSM buffers in CSM buffer headers.
- MONITOR=NO
- Specifies that CSM Buffer Monitoring will be deactivated.
- MONITOR=DYNAMIC
- Specifies that CSM Buffer Monitoring will be dynamically activated and deactivated. CSM dynamically activates CSM buffer Monitoring when CSM storage usage approaches the critical level. It will dynamically deactivate CSM buffer monitoring when CSM storage returns to a level slightly lower than the normal level. The default value is DYNAMIC.
Note:
- It is recommended to review the CSM usage and IVTPRM00 parmlib specifications for ECSA, fixed, and 64-bit HVCOMM CSM storage. CSM uses these values to determine the activation and deactivation points of Dynamic CSM buffer Monitoring. See z/OS MVS Initialization and Tuning Reference for details.
- When the CSM comes up, CSM Monitor status is dynamic by default. The operator can modify the status of CSM Monitor active, inactive, or dynamic. This status does not change when VTAM or TCP/IP goes down or comes up. It will stay the same until the system is re–IPL'd, or another MODIFY command is issued.
Examples
f vtamcs,csm,hvcomm=1024m
IVT5510I MODIFY ACCEPTED
IVT5517I CSM LIMITS PRIOR TO MODIFY CSM PROCESSING:
IVT5519I ECSA MAXIMUM = 100M - FIXED MAXIMUM = 2048M
IVT5595I HVCOMM MAXIMUM = 1000M
IVT5518I CSM LIMITS AFTER MODIFY CSM PROCESSING:
IVT5519I ECSA MAXIMUM = 100M - FIXED MAXIMUM = 2048M
IVT5595I HVCOMM MAXIMUM = 1024M
IVT5599I END
f vtamcs,csm,monitor=yes
IVT5510I MODIFY ACCEPTED
IVT5566I CSM MONITOR IS ACTIVE