SET TRANCLASS

Description

The SET TRANCLASS command allows you to change the limits that govern tasks within a particular transaction class. These are the maximum number of tasks that can run concurrently (the MAXACTIVE value) and the maximum number that can queue awaiting initial dispatch (the PURGETHRESH value).

Options

MAXACTIVE(data-value)

Specifies, as a fullword binary value, the largest number of tasks in the transaction class which can run concurrently. The value can be in the range 0-999.

Raising the MAXACTIVE limit has an immediate effect if the old value of MAXACTIVE has caused queuing, because CICS® dispatches queued tasks up to the new MAXACTIVE value. The effect of lowering MAXACTIVE, however, is gradual. Tasks in the class that are already running are allowed to complete normally, but new tasks are not dispatched until the number running drops below the new limit. If you lower MAXACTIVE to zero, you prevent any task in the class from starting execution until MAXACTIVE is increased.

PURGETHRESH(data-value)

Specifies, as a fullword binary value, one more than the maximum number of tasks in this class that can be queued awaiting initial dispatch. Queuing can occur either because the number of active tasks in the class is already at the MAXACTIVE value or because the maximum for the system has been reached (see the MAXTASKS option in the INQUIRE SYSTEM command). Tasks that arrive while the queue is at its PURGETHRESH limit are purged (abended with a code of AKCC).

The PURGETHRESH value for a class can be between 0-1000000. A value of zero means there is no purge threshold limit; that is, any number of tasks can be queued. A value of one means that no tasks can be queued.

Raising the PURGETHRESH limit allows more transactions to queue and has an effect only when a task is attached that would have been purged if the old value were in effect.

However, if you lower the PURGETHRESH limit beyond the current size of the queue, enough queued tasks are abended to reduce the queue to the new limit. If you raise MAXACTIVE at the same time you lower PURGETHRESH, CICS dispatches as many queued tasks as possible before purging queued tasks, to minimize the number of tasks that get abended. Tasks are abended in priority order, starting with the lowest priority task.

TRANCLASS(data-value)

Specifies the 8-character name of the transaction class that you are changing. If the class is one of the numbered classes used in earlier releases of CICS, its name is DFHTCLnn, where nn is the two-digit class number.

Conditions

INVREQ

RESP2 values:

2

The MAXACTIVE value is not in the range 0-999.

3

The PURGETHRESH value is not in the range 0-1000000.

NOTAUTH

RESP2 values:

100

The user associated with the issuing task is not authorized to use this command.

TCIDERR

RESP2 values:

1

The transaction class cannot be found.