Runtime Considerations › Multiple External Run Units Under CA ADS Batch

Multiple External Run Units Under CA ADS Batch

Preparing the system to handle multiple external run units (ERUs) for CA ADS Batch is a DBA or system administrator issue, not a programmer issue.

However, an CA ADS Batch application run at a Distributed Database System (DDS) site should be designed so that a single database run unit is maintained for the application's duration. It is particularly important that the application avoid saving and then restoring database currencies if the application's run unit is accessing a database at a different DDS node than the default node for central version operations.

An CA ADS Batch application's database requests are routed to the batch interface module (IDMSINTB). IDMSINTB passes the request through the CA IDMS SVC (for central version requests) or directly to DC/UCF (for local mode requests). In DC/UCF, the database request is handled as an external run unit as is any other batch database request.

At system generation, it is necessary to specify a value for the MAXIMUM ERUS parameter in the SYSTEM statement. An CA ADS Batch application occasionally requires up to five ERUs at the same time:

• User database run unit, required if a dialog is accessing the database
• Message run unit, required to retrieve message text from the dictionary
• Loader run unit, required to retrieve load modules from the load area

If the MAXIMUM ERUS count is exceeded at runtime, your CA ADS Batch will be unable to load modules (for maps, dialogs, and so forth). If you receive a message to this effect, verify that the MAXIMUM ERUS specification for the system is at least 3. This specification is made in the system generation SYSTEM statement.

Note: For more information, see the CA IDMS System Generation Guide.