Application design

Design your applications to run the sign-on transaction before any other transaction.

This keeps that any password check and any password changing separate from the application's own functions. In multitasking systems, it is possible for more than one sign-on transaction to start on parallel sessions. It is important that the code dealing with application-level ALLOCATE requests, serializes the sign-on process to completion, thus ensuring both flow as signed-on.

To record the date and time of a previous successful sign-on, the CICS® PEM server sign-on program extracts password data from the ESM before it performs sign-on. If your system uses shared userids, and two users attempt to sign on at the same time, or if a user is multitasking, the time values returned to the PEM client for the current sign-on may not be the same as the timestamp recorded on the ESM database. Remember this if you are writing an application that is to run on multiple systems, and depends on the sign-on time returned to the PEM client. (This situation should not apply on a single system, provided the sign-on process is serialized as suggested.)

If PV is being used, and the interval specified in PVDELAY is exceeded, and the userid is removed from the PV sign on from list, applications must allow for the sign-on process to be serialized again.