Record-Level Sharing CF Caching

VSAM record-level sharing allows multiple levels of CF caching for DFSMS cache structures that are defined in the active storage management subsystem (SMS) configuration.

VSAM RLS has multiple levels of CF caching. The value of the SMS DATACLAS RLS CF Cache Value keyword determines the level of CF caching.

All active systems in a sysplex must have the greater than 4K CF caching feature before the function is enabled.

To set up RLS CF caching, use the following values:

ALL or UPDATESONLY or NONE or DIRONLY for the SMS DATACLAS RLS CF Cache Value keyword
To allow greater than 4K caching of DFSMS VSAM data sets open for RLS processing, you need to make the following changes:
- You can change the value of the SMS DATACLAS RLS CF Cache Value keyword if you do not want caching of all VSAM RLS data:
  ALL
  
  Indicates that RLS is to cache VSAM index and data components in the coupling facility. ALL is the default.
  
  NONE
  
  Indicates that RLS is to cache only the VSAM index data. The data components are not to be placed in the cache structure.
  
  UPDATESONLY
  
  Indicates that RLS is to place only WRITE requests in the cache structure.
  
  DIRONLY
  
  indicates that RLS will not cache data or index part of the VSAM data set in the coupling facility cache structure. In this case, RLS will use the XCF cache structure to keep track of data that resides in permanent storage (DASD) and local storage but data or index CIs are not stored in the cache structure itself.
- VSAM honors the RLS CF Cache Value keyword only when you specify RLS_MaxCfFeatureLevel(A) and all systems in the sysplex can run the greater than 4K caching code.
  To determine the code level on each system in the sysplex and whether the RLS CF Cache Value keyword is honored, use the D SMS,SMSVSAM, D SMS,SMSVSAM,ALL, and D SMS,CFCACHE() operator commands. When DFSMS cache structures connect to the system, VSAM RLS issues an IGW500I message to indicate that greater than 4K caching is active. The cache structures connect to the system through the first instance of a data set opened on each system.
You can specify the following values for the RLS_MaxCfFeatureLevel keyword:
- A—This value allows greater than 4K caching if all active VSAM RLS instances in the sysplex have the correct level of code.
- Z—This is the default value if you do not specify RLS_MaxCfFeatureLevel in the active SMS configuration. Greater than 4K caching is not allowed.
RLS_MaxCfFeatureLevel keyword in the SETSMS command
RLS_MaxCfFeatureLevel keyword in the SET SMSxx command
RLS_MaxCfCacheFeatureLevel in the D SMS,OPTIONS command