DFSSQxxx member of the IMS PROCLIB data set

You can find an example of the DFSSQxxx member of the IMS PROCLIB data set, DFSSQ999, in library SDFSSLIB.

The parameters for DFSSQxxx can also be specified on the DFSDFxxx member of the IMS PROCLIB data set. See DFSDFxxx member of the IMS PROCLIB data set for more information.

Syntax

You can use the IMS Syntax Checker to modify this member of the IMS PROCLIB data set.

Usage

A DFSSQxxx member consists of one or more fixed-length character records (the configuration data set can be of any LRECL greater than eight, but it must be fixed record format). The rightmost-eight columns are ignored but can be used for sequence numbers or any other notation. Keyword parameters can be coded in the remaining columns in free format, and can contain leading and trailing blanks. You can specify multiple keywords in each record; use commas or spaces to delimit keywords. Statements that begin with a “*” or “#” in column 1 are comment lines and are ignored. Additionally, comments can be included anywhere within a statement by enclosing them between “ /* ”and “*/”, for example, /* PROCLIB comments */. Values coded in this member of the IMS PROCLIB data set are case sensitive. In general, you should use uppercase for all parameters.

Errors encountered during DFSSQxxx member processing cause IMS initialization to terminate.

Parameters

CQS=

Specifies the one- to eight-character name of the member of the IMS PROCLIB data set that contains one of the following:

• The procedure for the CQS address space.

  When shared message queues are requested the IMS control region automatically starts the CQS procedure during IMS initialization. The default procedure name is CQS.

• The START command.

  The START command begins in column 1 with the characters START. The START command and its parameters must not extend beyond column 71.

  When shared message queues are requested, the IMS control region issues the user-specified START command to start the CQS address space.

CQSSSN=

Specifies the name for the CQS address space. The value must be 1 - 4 alphanumeric characters. IMS uses this name to connect to the proper CQS address space. When connecting IMS to CQS, you must specify the same value on CQSSSN= and on the SSN= parameter of the CQSIPxxx member of the IMS PROCLIB data set for the target CQS. The parameter is required and no default exists.

As many as 32 different IMS control regions can specify the same CQSSSN= parameter.

EMHQ=

An optional parameter that specifies the 1- to 16-character name of the primary structure that contains the shared expedited message handler queues (EMHQs). In a shared-queues environment when Fast Path is installed, the presence of this statement indicates that the EMHQ structure, along with its associated log structure, checkpoint data set, and structure recovery data set are required. To disable shared expedited message handler processing, you can remove the EMHQ statement from this member, and the EMHQ structure, along with its associated log structure, checkpoint, and structure recovery data sets, are not required.

If you do not want to utilize an EMHQ structure for an IMS system, you need to delete the STRUCTURE statement for the EMHQ from the CQSSLxxx member of the IMS PROCLIB data set. If you do not want to utilize an EMHQ structure for all the IMS systems in a sysplex, you also need to delete the STRUCTURE statement for the EMHQ from the CQSSGxxx member of the IMS PROCLIB data set.

When you do not use an EMHQ structure, you should also do the following:

• In the CRFM policy, delete the STRUCTURE definitions for the EMHQ structure and its CQS log.
• In the z/OS® Logger Structure Definition policy, delete the LOGSTREAM definition for CQS log for an EMHQ structure.
• If you are using an IMS automation program for any command that deals with an EMHQ structure, delete the command in the automation.

If you specify an EMHQ= structure, you must

• specify shared message queues on the MSGQ= parameter.

  IMS requires the message queues to process system messages that result from Fast Path activity. If the EMH queues are built in a coupling facility structure, the message queues must also be in a structure.

• Specify FP=Y as a control region execution parameter.

The name you specify for EMHQ= must not be the same as the name you specify for MSGQ=. The name must also be specified to CQS on the STRNAME= parameter in the CQSSLxxx and CQSSGxxx members of the IMS PROCLIB data set.

This parameter is valid only when Fast Path is installed.

MSGQ=

Specifies the one- to sixteen-character name of the primary structure that contains the shared message queues. If the message queues are built in a coupling facility structure, the EMH queues, if used, must also be in a structure.

The name you specify for MSGQ= must not be the same as the name you specify for EMHQ= The name must also be specified to CQS on the STRNAME= parameter in the CQSSLxxx and CQSSGxxx members of the IMS PROCLIB data set.

SQGROUP=

Specifies a one- to five- character identifier. IMS concatenates this identifier to DFS to create the z/OS cross-system coupling facility IMS shared queues group name. You must specify the same identifiers for all IMS subsystems that share the same set of structures. You can use the same identifier for the CQSGROUP= parameter in the CQSIPxxx member of the IMS PROCLIB data set. This parameter is required and there is no default.

WAITRBLD=Y│N

Specifies whether activity against the EMHQ structure waits while the structure is being rebuilt. If you specify Y (yes), all activity against the EMHQ structure waits until the structure rebuild completes. If you specify N (no), activity against the EMHQ structure continues while CQS rebuilds the structure.

The value specified for this keyword remains in effect for the life of the structure and cannot be changed.

Restriction: This parameter does not apply to the MSGQ. The MSGQ must wait for rebuild to complete before activity can resume.

If you change the WAITRBLD= parameter, you must first deallocate the fast path structure.