Use this procedure if you have identified a failing VTAM® module in one of the other procedures (abnormal end, message, or loop). Figure 1 shows an overview of the failing module procedure.

Figure 1. Overview of the failing module procedure

The following procedure describes each step shown in Figure 1.

1. Determine the caller of the service routine.

   The failure might have occurred in a VTAM service routine used for many purposes. Determine the caller of the service routine. Use the save area conventions in Using save-area module linkage conventions—Subarea, or if you know the save area address, use the ISTVSAVE CLIST.

2. Examine the work element structure.

   If your problem type is an abnormal end or loop, and the module is dispatched under control of VTAM PSS, find the CRA/RPH associated with the process. (See step 10 in the wait procedure.) The RPHWEA field (at offset X'1C') usually points to the work element associated with the process at the time it was dispatched. To identify the work element, see Using save-area module linkage conventions—Subarea.

   From the work element, it might be possible to identify an SNA request/response type, an operator command, or an application program request that ultimately caused the process to receive control. Add this request or command name to your documentation list.

   If the RPHWEA field does not point to the work element, continue with step 3.

3. Have VIT information available.

   Use the VIT options PSS and SMS to get more information about how the failing module received control or where the relevant control blocks are found. To obtain the address of the work element and the module name of the process entry point, use the last dispatch (DSP) entry for the failing process.

   Continue with Reporting the problem to IBM.