Managing resource and descriptor definitions

With dynamic resource definition (DRD) enabled, you can perform several tasks to manage the resource and descriptor definitions for your IMS system.

With DRD enabled, you can use the CREATE, UPDATE, DELETE, and EXPORT and IMPORT type-2 commands to perform the following tasks.

Create application program, database, routing code, transaction resources, or descriptors
Update resources or descriptors
Delete resources or descriptors
Query definitional attributes of resources or descriptors (by using the QUERY command)
Export resource and descriptor definitions from IMS to a resource definition data set (RDDS) or an IMSRSC repository
Import resource and descriptor definitions from an RDDS or a repository into IMS, which creates new resources and descriptors and updates existing resources and descriptors

With DRD, you can also create, update, and delete MSC resources (LTERM, MSLINK, MSNAME, MSPLINK), but cannot import them. MSC resources do not support RDDS or the EXPORT command.

Note: MSC resources do not have descriptors.

Issue the type-2 commands from a single point of control (SPOC) application (for example, the TSO SPOC that is shipped with IMS). You can also use the IMS Manage Resources application that is available from the IMS Application Menu (option 2).

Resource descriptors are templates that can be used to define new resources and descriptors. IMS supplies four resource descriptors, one for each resource type. The descriptors contain the IMS-system default values for each resource attribute. These IMS-supplied descriptors cannot be deleted or modified. IMS-supplied descriptors are not exported to the repository or RDDS. The IMS-supplied resource descriptors are as follows:

DFSDSDB1 (database descriptor)
DFSDSPG1 (application program descriptor)
DBFDSRT1 (Fast Path routing code descriptor)
DFSDSTR1 (transaction descriptor)

You can use the IMS-supplied descriptors as models for creating resources or additional descriptors. You can also create descriptors without modeling them after existing descriptors. Initially, the IMS-supplied descriptors are set as the default descriptors, but you can designate one of your own descriptors as the default by using the DEFAULT(Y) keyword on the CREATE or UPDATE command.

When you create a resource without specifying a model (that is, you do not specify the LIKE keyword), any attribute values that are not specified on the CREATE command are inherited from the default descriptor. When you create a resource that is modeled from a descriptor (using the LIKE keyword), any attribute values that are not specified on the CREATE command are inherited from the descriptor.

Similarly, when you create a resource using an existing resource as a model (using the LIKE keyword), any attribute values that are not specified on the CREATE command are inherited from the existing resource.

Tip: To ease the transition from using the online change process to using DRD, you can create runtime resource definitions using the batch system definition process and then enable DRD so that you can use the DRD commands.

IMS systems can export resources that are defined by the batch system definition process and resource definitions that have been created or updated dynamically, to an RDDS or an IMSRSC repository, by using the EXPORT DEFN command. You can also set up your system for automatic export to an RDDS or an IMSRSC repository.

These resource definitions can then be imported from the RDDS into an IMS system during a cold start. To ensure that your changes are recovered across a cold start: export all IMS definitions to an RDDS or repository before shutting it down. For RDDSs, you can also set up your system to automatically export your resource and descriptor definitions at checkpoint time. Set up your system to automatically import the definitions from the RDDS or repository during cold start processing.

In situations when IMS receives a message for an unknown destination, you can also use the Destination Creation exit routine (DFSINSX0) to define a new transaction to IMS for that message and, if necessary, define the application program that is associated with the transaction.

Attention: DRD changes are not necessarily made across all IMS systems in an IMSplex. Changes might be successful on some IMS systems but fail on others. You must verify that changes have been made across all systems.

The figure that follows shows the ISPF panel for managing resources.

Figure 1. IMS Manage Resources main panel

   Help                                                           
 ------------------------------------------------------------------------------ 
 SPOC                         IMS Manage Resources                              
                                                                                
 Command ===>                                                                   
                                                                                
 Select an action and press Enter.                                              
                                                                                
                                                                                
 * Action . . . . . .    1. Create new resources                                
                         2. Delete resources                                    
                         3. Query resources                                     
                         4. Update resources                                    
                         5. Import resources                                    
                         6. Export resources                                    
                         7. Manage RDDS