CICS / WebSphere

The CICS Data Sharing Servers

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The CICS System Definition Guide describes the shared temporary storage server parameters you can use to provide early warning about when a structure is nearing capacity. 

Resource Definition for Temporary Storage Data Sharing  

Having defined a TS pool via IXCMIAPU, a TSMODEL needs to be defined using CEDA to use shared temporary storage. Figure 3 shows a TSMODEL. The PRefix specifies the character string used for matching queue names. It can contain wildcard characters; it isn’t limited to the leading characters for a queue name. It’s also possible to specify a generic name by using the plus (+) sign in a character string to indicate any valid character is possible in that position. PRefix is the RDO equivalent of the DATAID parameter provided with the TST. 

The location of a temporary storage queue can be specified as auxiliary or main (for traditional temporary storage queues). This attribute is ignored if a shared attribute of POolname is provided, too. Whatever location is given on an Application Program Interface (API) command is ignored, and that given in the TSMODEL is used. Also, the RECovery and POolname attributes are mutually exclusive as recoverable shared temporary storage queues aren’t supported. 

Although shared temporary storage isn’t recoverable, shared data will persist across CICS restarts (including initial starts). This differs from main and auxiliary temporary storage data (which doesn’t survive an initial restart of CICS). The shared data resides on the coupling facility, independent of a given CICS system. As such, there are housekeeping implications in tidying up unwanted shared temporary storage queues when appropriate. 

Defining a Shared Temporary Storage Server Region  

A shared temporary storage pool consists of an XES list structure, which is accessed through a cross-memory queue server region. A shared temporary storage pool is made available to a z/OS image by starting up a shared temporary storage queue server region for that pool. This invokes the shared temporary storage server region program DFHXQMN, which must reside in an APF-authorized library. A shared temporary storage server region must be activated before the CICS region attempts to use it. 

DFHXQMN requires some initialization parameters, of which the pool name, a SYSPRINT DD statement for the print file, and a SYSIN DD statement for the server parameters are mandatory. Other optional parameters may be specified for debugging and tuning purposes. 

Figure 4 shows a sample start-up job for a shared temporary storage server region, showing some of the parameters you can specify. 

6 Pages