Configuring the resource structure for an IMSplex

The resource structure, supported by the Common Queue Server (CQS), is the repository for resources managed by RM. CQS manages uniquely named client resources that are shared within a single IMSplex by using the coupling facility list structures.

The resource structure is optional; however, if there is no resource structure certain IMSplex functions cannot be used.

Clients can use the resource structure to share resource information, control block information, and so on. The resource name is unique within the structure. Resources can be updated, deleted, or queried. A primary coupling facility list structure is used to contain the resources. Resource structures do not support an overflow structure.

CQS does not support structure recovery, structure checkpoint, or overflow processing for resource structures. Also, to improve performance, changes to resource structures are not logged. However, for recovery of resources, resource structures can be automatically duplexed by specifying so in the CFRM policy.

CQS defines the attributes of the resource structure the first time it connects to the structure. It defines the resource structure as a persistent, ENTRYKEY list structure and the list entries on the resource structure are defined to contain an adjunct area and a data entry. The resource structure is defined to permit SVC dumps, structure alter, and autorebuild.

Recommendation: Use multiple RMs and a resource structure in your IMSplex. Without a resource structure, you cannot use the global resource-sharing capabilities of RM. Additionally, without a resource structure, you can start only one RM. If that one RM goes down, you do not have a backup RM. However, if you do not have a resource structure and are in a DBCTL environment, you can still perform global online changes with one RM.

Configuring a simplified IMSplex for the type-2 command environment

If you want to use type-2 commands and you have a standalone IMS system or multiple IMS systems that only share databases, you can define an IMSplex without RM. This creates a simplified IMSplex with CSL.

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