EXECUTION DIAGNOSTIC FACILITY - IBM Mainframe

The Execution Diagnostic Facility is a CICS supplied transaction, which monitors the execution of an application, program as an interactive debugging aid. EDF monitors an application program by executing and suspending the program and displaying the execution status at the following points:

  • Transaction Initiation
  • Start of each CICS command
  • Completion of each CICS command
  • Program Termination
  • Normal or Abnormal Task termination.

The following information can be displayed

  • Values of E1B
  • Program's Working-storage area
  • Last 10 commands executed
  • Contents of any address location in the region
  • Current, next or previous application screen
  • Contents of the TSQ

When the commands are displayed, the application programmer is given the ability to make changes to the commands and conditions, display and alter the working storage, modify the return codes and the contents of the EIB fields, bypass the display of undesired commands, etc. During the execution the programmer can force the program to be ABENDed. The EDF can be terminated after the desired point in the program execution. EDF is run as a CICS transaction and can be initiated by entering the transaction id CEDF on a cleared screen and pressing the ENTER key. Another way in which the EDF can be executed is called the dual screen mode, where the application transaction and EDF monitoring are executed on two different terminals. For initiating EDF in the dual mode you will have to type CEDF tttt where 'tttt is the terminal id of the terminal to which the application transaction is to be executed. When EDF is run on a single terminal (single screen mode), program maps will be displayed interspersed between the displays of the EDF screens. In the dual screen mode, one screen will display the execution of the application program while the other will display and monitor the EDF screens. So the procedure for running EDF in single screen mode is as follows:

  • Clear screen and type CEDF and press ENTER key
  • THIS TERMINAL: EDF MODE ON will be displayed.
  • Clear the screen.
  • Type the transaction id and press the ENTER key.
  • The Program initiation screen will be displayed.

Program Initiation Screen

This screen displays the EIB as it exists upon the initial entry into the program. Line 1 is same for all the EDF screens and contains the transaction id, the program name, a sequential task number assigned by the system, etc. The DISPLAY=00 reflects the current screen being displayed. As succeeding screens are displayed, it is possible to view the previous screens and then the DISPLAY will be decremented by 1 for each prior screen displayed. Line 2 displays the status of the EDF screen being displayed. For this screen it is PROGRAM INITIATION. Then the screen shows the values of the EIB fields and the PF keys and their functions.

About to Execute Command Screen

EDF displays a screen prior to the execution of a CICS command. At this point if you wish the argument values may be modified. The OFFSET field shown at the bottom is the program CLIST offset and may be used to locate the CICS command about to execute. The LINE parameter gives the line number corresponding to the translator printout of the CICS program. LINE will be only displayed if the program was translated using the DEBUG option. The EIBFN is the EIB function code for the command to be executed.

Command Execution Complete Screen

At the completion of a CICS command EDF interrupts the execution and displays the Execution Completion screen. ABEND, RETURN and XCTL do not display a command execution complete screen. The EDF display two new fields the RESPONSE field and the EIBRESP. The Response will be NORMAL unless a handle condition has been invoked, in which case the invoked condition will be displayed in the RESPONSE field. If the program encounters an ABEND, EDF will intercept it and display the status of the program at the ABEND status display. This screen shows useful information for debugging such as EIB, PSW, ABEND code, etc

Program Completion Screen

At the end of the program execution EDF displays the program termination screen.

Task Termination Screen

For pseudo-conversational programs at the end of one task, EDF will display a transaction termination screen. If you specify "fES' the pseudo-conversational process monitoring will be continued. If 'NO' is specified in the task termination screen EDF will end the EDF session.

Working Storage Screen

Any part of the working-storage area of the application program can be displayed and modified during an EDF session. The procedure is as follows:

  • Press PF3 to switch to hexadecimal (HEX) mode.
  • At the command completion screen the working storage address will be shown after the AT (say for example AT X'000F2D3C).
  • Press PF5 to display working storage. It will display the working storage from the beginning of the working-storage area.
  • PF7 and PF8 can be used to scroll forward and backward. You can also type the address that you want at the ADDRESS field and press the ENTER key to get the Working storage from that point.

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