Implementing an XEIIN global user exit

The XEIIN global user exit can be useful if an overlay is not being detected until CICS® task termination is doing the final freeing of storage. CICS® can detect a Storage Accounting Area (SAA) overlay either during an explicit FREEMAIN or during task termination. If detected at task termination, the task is not abended by CICS® and hence Z Abend Investigator is not invoked. CICS® attempts to take a system dump, with dump code SM0102, however if CICS® system dumps are being suppressed, further analysis is not possible.

To assist with SAA overlays Z Abend Investigator provides a program that can optionally be installed in the XEIIN global user exit. If installed, this program, at each EXEC CICS® RETURN statement, validates all the CICS® storage accounting areas for the current task. If an overlay is found, then one of two actions can be performed:

A call can be made to take a CICS® transaction dump with dumpcode HFZS.
If Z Abend Investigator is installed in the XDUREQ global user exit, then this transaction dump is analyzed in the normal manner with a history file fault entry being created.
An SDUMP of the CICS® region can be taken.
The request to take this SDUMP is made by the HFZS subsystem, and as such, it is not affected by the CICS® system dump suppression setting. If a SDUMP is captured, then it can then be analyzed interactively by way of the File menu option 5.

Enabling the Z Abend Investigator XEIIN global user exit program, and setting which action should be performed, is done using the Z Abend Investigator supplied CFA transaction. Unlike the other Z Abend Investigator CICS® exits, there is no option to enable the XEIIN exit during CICS® PLT processing.

When invoked, the initial CFA display is similar to the following:

                   Z Abend Investigator Control Transaction                        
Options: I=Install U=Uninstall                                               
                  Current Status/Error Message                               
_ XPCABND         Installed                                                  
_ XDUREQ          Installed                                                  
_ LE Exit         Installed                                                  
_ SDUMP Screening Installed                                                  
_ XEIIN           Uninstalled   
                                                                             
        Current    HWM  Setting    MWS                                       
Active     0000   0001     0001                                              
Waiting    0000   0000     0017   0000                                       
                                                                             
                                                                             
                                                                             
                                                                             
                                                                             
HFZTRACE OFF DeferredReport ON                                               
                                                                             
PF1=Help PF3=Exit PF4=Opts PF5=Clear FND Area PF9=IVP PF11=TRACE ENTER=Update

From this display, an "I" can be entered next to XEIIN to install the exit. A screen similar to the following is then displayed:

                   Z Abend Investigator Control Transaction                        
Options: I=Install U=Uninstall                                               
                  Current Status/Error Message                               
_ XPCABND         Installed                                                  
_ XDUREQ          Installed                                                  
_ LE Exit         Installed                                                  
_ SDUMP Screening Installed                                                  
_ XEIIN           Installed   N TXN dump N SDUMP Set at least one option to Y
                                                                             
        Current    HWM  Setting    MWS                                       
Active     0000   0001     0001                                              
Waiting    0000   0000     0017   0000                                       
                                                                             
                                                                             
                                                                             
                                                                             
                                                                             
                                                                             
                                                                             
                                                                             
                                                                             
HFZTRACE OFF DeferredReport ON                                               
                                                                             
PF1=Help PF3=Exit PF4=Opts PF5=Clear FND Area PF9=IVP PF11=TRACE ENTER=Update

In this screen, enter "Y" next to either TXN dump or SDUMP to set the action to take when an SAA overlay is detected.

The I (Install) option must be used each time the TXN or SDUMP field is changed.

Note: Although there is no overhead in having any other Z Abend Investigator exit installed/enabled, the XEIIN exit is invoked by CICS® on every EXEC CICS® command, and hence does incur a small overhead. As such, it is recommended to only use the XEIIN exit when needing to investigate SAA overlays.