IBM SC34-7012-01 manual Indoubt failure recovery, Files

distinguishes between a commit failure where recoverable work was performed, and one for which only repeatable read locks were held.

Indoubt failure recovery

The CICS recovery manager is responsible for maintaining the state of each unit of work in a CICS region.

For example, typical events that cause a change in the state of a unit of work are temporary suspension and resumption, receipt of syncpoint requests, and entry into the indoubt period during two-phase commit processing.

The CICS recovery manager shunts a unit of work if all the following conditions apply:

vThe unit of work has entered the indoubt period.

vThe recovery manager detects loss of connectivity to its coordinator for the unit of work.

vThe indoubt attribute on the transaction resource definition under which the unit of work is running specifies WAIT(YES).

vThe conditions exist that allow shunting. See ../dfht1/topics/dfht12z.dita for a complete list of conditions.

Files

When file control shunts its resources for the unit of work, it detects that the shunt is being issued during the first phase of two-phase commit, indicating an indoubt failure.

Any active exclusive lock held against a data set updated by the unit of work is converted into a retained lock. The result of this action is as follows:

vNo CICS region, including the CICS region that obtained the locks, can update the records that are awaiting indoubt resolution because the locks have not been freed.

vOther units of work do not wait on these locked records, because the locks are not active locks but retained locks, requests for which cause CICS to return the LOCKED response.

For information about types of locks, see “Locks” on page 14.

For data sets opened in RLS mode, interfaces to VSAM RLS are used to retain the locks. For VSAM data sets opened in non-RLS mode, and for BDAM data sets, the CICS enqueue domain provides an equivalent function. It is not possible for some of the data sets updated in a particular unit of work to be failed indoubt and for the others not to be.

It is possible for a unit of work that has not performed any recoverable work, but which has performed repeatable reads, to be shunted when an indoubt failure occurs. In this event, repeatable read locks are released. Therefore, for any data set against which only repeatable reads were issued, it is possible to access the records, and to open the data set in non-RLS mode for batch processing, despite the existence of the indoubt failure. The INQUIRE UOWDSNFAIL command distinguishes between an indoubt failure where recoverable work has been performed, and one for which only repeatable read locks were held. If you want to open the data set in non-RLS mode in CICS, you need to resolve the indoubt failure before you can define the file as having RLSACCESS(NO). If the unit of work has updated any other data sets, or any other resources, you should try to resolve the indoubt correctly, but if the unit of work has only performed repeatable

84CICS TS for z/OS 4.1: Recovery and Restart Guide