From Page 4 of the Data Class Define panel, use the DOWN command to view Page 5, on which you specify Shareoptions and RLS attributes.

Shareoptions

Specifies how end users can share a component or cluster.

The Xregion value specifies the amount of sharing allowed among regions within the same system, or within multiple systems using global resource serialization (GRS). You can specify the following values:

1

Any number of users can read the data set at one time, or only one can write to it. This setting does not allow any type of non-RLS access when the data set is already open for RLS processing.

2

Any number of users can read the data set at one time, and only one can write to it. If the data set is already open for RLS, non-RLS users can read the data set but cannot write to it. If the data set has been opened for non-RLS output, an RLS open fails.

Requirement: You must apply APARs OW25251 and OW25252 to allow non-RLS read access to data sets already open for RLS processing.

3

Any number of users can share the data set, and each is responsible for maintaining read and write integrity. This setting does not allow any type of non-RLS access when the data set is already open for RLS processing.

4

Any number of users can share the data set, and buffers used for direct processing are refreshed for each request. This setting does not allow any type of non-RLS access when the data set is already open for RLS processing.

The Xsystem value specifies the amount of sharing allowed among systems. You can specify the following values:

3

Any number of users can share the data set, and each is responsible for maintaining read and write integrity.

4

Any number of users can share the data set, and buffers used for direct processing are refreshed for each request.

If values are not specified explicitly or in the data class, VSAM defaults are used.

RLS CF Cache Value

Specifies the amount of data that will be cached. This keyword is honored only when RLS_MaxCfFeatureLevel(A) is active in the sysplex.

DFSMS CF cache structures are connected to the system when the first VSAM RLS instance is opened on the system. At this time, message IGW500I is issued to indicate whether the RLS CF Cache Value keyword is honored.

You can specify the following values:

ALL

Indicates that VSAM index and data components will be cached. ALL is the default.

NONE

Indicates that only the VSAM index data will be cached. The data components will not be placed in the cache structure.

UPDATESONLY

indicates that only WRITE requests will be placed in the cache structure.

DIRONLY

indicates that RLS will not cache the data or index parts 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 in local storage but data or index CIs are not stored in the cache structure itself.

RLS Above the 2-GB Bar

Specifies whether the SMSVSAM address space can take advantage of 64-bit addressable virtual storage during VSAM RLS buffering.

You can specify the following values:

Y

Indicates that VSAM RLS buffers can reside above the 2-gigabyte bar. This setting is recommended for best performance of high-volume applications that use VSAM RLS buffering.

N

Indicates that VSAM RLS buffering is limited to storage below the bar. N is the default.

Extent Constraint Removal

Specifies whether data sets are allowed to be extended beyond 255 extents.

CA Reclaim

Specifies whether the DASD space for empty control areas (CAs) will be reclaimed for key-sequenced data sets (KSDS). Specify one of the following:

Y

Indicates that DASD space for empty CAs will be reclaimed. This is the default.

N

Indicates that DASD space for empty CAs will not be reclaimed.

The value for CA Reclaim is always saved in the catalog, but is used only if the CA reclaim function is enabled in the IGDSMSxx member of PARMLIB or with the SETSMS command.

The setting for CA Reclaim for a data class is processed only when a catalog entry for a KSDS is defined. If you need to change the CA reclaim setting for an existing KSDS based on the contents of the data class, either use the ALTER command for the KSDS or delete and define the KSDS to use the value in the data class.

For more information, see the topic about CA reclaim in z/OS DFSMS Using Data Sets.