Using DBRC to control database allocation and access

DBRC allows you to control access to data by IMS systems that participate in data sharing. Using DBRC, you can modify, initiate, and delete the current status indicators in the RECON data set to change the access intent of online IMS systems and the share level of registered databases.

Your data sharing environment depends on the status of the databases and IMS systems indicated in the RECON data set.

You can modify the access intent indicator using a form of the /START or UPDATE command.

You can modify the share level indicator using a form of one of the DBRC online change commands, /RMCHANGE.

Denial of authorization

The following occurs if DBRC (in a data sharing environment) responds to authorization requests but fails to obtain authorization for an application program:

  • You receive message DFS047A identifying the database.
  • IMS schedules the application program's PSB without database access. IMS abnormally terminates a BMP or MPP with abend U3303 only if it tries to access the database.
  • IMS abnormally terminates batch and utility regions with abend U0047.

Changing database access intent

Use one of the following commands to change the access intent that you declare during system definition, where dbx is the database name and xx is the new access intent:

  • /START DATABASE dbxACCESS=xx
  • UPDATE DB START(ACCESS) SET(ACCTYPE(BRWS,EXCL,READ,UPD))
For the /START DATABASE dbxACCESS=xx command, values for xx are:
EX
Exclusive use
UP
Update access
RD
Read access
RO
Read-only access

This command is local; it affects only the IMS system on which you enter it. The GLOBAL keyword is not valid with the ACCESS= keyword. If you need to change the access level for a shared database across the sysplex, you must enter this command on each IMS system that shares the database.

The UPDATE DB START(ACCESS) SET(ACCTYPE(BRWS,EXCL,READ,UPD)) command can be either local or global.

In order to change the access intent for a DEDB, you must stop all PSBs that access any of the areas in the DEDB. You might also have to stop regions that have wait-for-input (WFI) transactions scheduled for the DEDB.