APPC/MVS Timeout Service

Using APPC/MVS™ Timeout Service, you can indicate the maximum time interval an application waits before terminating a conversation and regaining control from APPC/MVS callable services.

When APPC/MVS does not respond to an APPC call, due to a network delay for instance, the dependent region hangs and the caller cannot regain control.

The timeout feature is activated at startup by specifying the APPCIOT=(mmmm:ss,mmmm) parameter in the DFSDCxxx member of the IMS.PROCLIB data set. The APPC time-out values are specified in minutes (mmmm) and seconds (ss). Valid values for mmmm are 00 to 1440. Valid values for ss are 00 to 59. If APPCIOT=00, there is no time-out detection. When a transaction is terminated due to timeout, messages DFS1965E and DFS1959E are sent to the MTO terminal and the z/OS® console. The timeout value can be changed using the /CHANGE command.

For synchronous APPC conversations, if APPC timeout is active, then IMS uses ATBSTO6 service (SET_TIMEOUT_VALUE) to set the timeout value for each conversation.

For asynchronous APPC conversations, if APPC timeout is active, then IMS sets the timeout value when the conversation gets allocated. In either case, the timeout value is active until the conversation is deallocated, which occurs, in the case of IMS conversational transactions, when the IMS conversation ends.

Common Programming Interface Communications (CPI-C) transactions are not automatically supported by APPC/MVS Timeout service, but can exploit APPC/MVS Timeout service using ATBSTO5 service provided the proper coding is supplied.

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