Defining temporary storage pools for temporary storage data sharing

You define a temporary storage (TS) pool as a temporary storage list structure in a coupling facility by using coupling facility resource manager (CFRM) policy statements.

About this task

To use TS data sharing, main or auxiliary storage for your TS queues is replaced by one or more TS pools, where the scope and function of each TS pool is similar to a queue-owning region (QOR).

Each TS pool is defined, using MVS™ cross-system extended services (XES), as a keyed list structure in a coupling facility. Therefore you must define the pool using the coupling facility resource manager (CFRM) policy statements. You use the CFRM policy definition utility, IXCMIAPU, to specify the size of the list structures required, and their placement in a coupling facility. For an example of this utility, see member IXCCFRMP in the SYS1.SAMPLIB library (see Administrative data utility for CFRM policy data in z/OS MVS Setting Up a Sysplex. An example of a definition statement is shown in Figure 1.

Figure 1. Example of defining the estimated size of a list structure

  STRUCTURE  NAME(DFHXQLS_PRODTSQ1)
    SIZE(8192)
    INITSIZE(10240)
    PREFLIST(FACIL01,FACIL02)

The name of the list structure for a TS data sharing pool is created by appending the TS pool name to the prefix DFHXQLS_, giving DFHXQLS_poolname. When defined, you must activate the CFRM policy using the MVS operator command SETXCF START.

When a list structure is allocated, an initial size and a maximum size can be specified in the CFRM policy. All structure sizes are rounded up to the next storage increment for the coupling facility level (CFLEVEL) at allocation time. For example, sizes are rounded up to the nearest 1 MB for CFLEVEL 16. Provided that space is available in the coupling facility, a list structure can be dynamically expanded from its initial size towards its maximum size, or contracted to free up coupling facility space for other purposes. If the initial structure allocation becomes full, the structure does not expand automatically, even if the structure allocated is less than the specified maximum size. To expand a list structure when the allocation becomes full, you can expand it (up to its maximum size) using the following SETXCF command:

SETXCF START,ALTER,STRNAME=DFHXQLS_poolname,SIZE=nnnn

Defining the CFRM policy statements for a list structure does not create the list structure. A TS server creates the list structure during its initialization. See Setting up and running a temporary storage server.

If the server connection fails, there are implications for coupling facility data tables. See Server connection management and Named counter recovery.

For further information about defining list structures, see the following z/OS® information: