1. Control Operations Day 5

2. 2 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 Objectives Task Control –ENQUEUE/DEQUEUE –SUSPEND Program Control –Usage of COMMAREA in LINK, XCTL –RETURN –LOAD, RELEASE Storage Control –GETMAIN –FREEMAIN Interval Control –ASKTIME, FORMATTIME –START, ATI –CANCEL, RETRIEVE –DELAY, POST, WAIT EVENT

3. 3 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 Task Control SUSPEND –Suspend a task –To relinquish control to a task of higher dispatching priority –Control returns to the task issuing the command when there is no other task of higher priority to be processed ENQ/DEQ –Schedule the use of a resource by a task –Protects the resource from concurrent use by more than one task ENQ RESOURCE (data-area) [LENGTH (data-value)] [NOSUSPEND] Conditions: ENQBUSY, LENGERR DEQ RESOURCE (data-area) [LENGTH (data-value)] Conditions: LENGERR

4. 4 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 Program Control Commands XCTL LINK RETURN ABEND LOAD RELEASE

5. 5 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 Logic Levels CICS PGM A LINK B RETURN PGM C LINK D RETURN PGM B XCTL C PGM D RETURN LEVEL 0 LEVEL 1 LEVEL 2 LEVEL 3 CICS PGM A LINK B RETURN PGM C LINK D RETURN PGM B XCTL C PGM D RETURN LEVEL 0 LEVEL 1 LEVEL 2 LEVEL 3

6. 6 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 XCTL EXAMPLE EXEC CICS XCTL PROGRAM (‘example3’) COMMAREA (ws-commarea) LENGTH (100) END-EXEC. This causes control to be passed to ‘example3’, with 100 bytes of data.

7. 7 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 LINK EXAMPLE EXEC CICS LINK PROGRAM (‘example3’) COMMAREA (ws-commarea) LENGTH (100) END-EXEC. The calling program expects control back. Control to example3 with 100 bytes of data.

8. 8 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 XCTL Vs LINK XCTL does not expect control back. Handle conditions in the main program are not available to the called program. Establish new handle conditions. LINK expects control back. Handle conditions in the calling program are needed again. Hence use PUSH and POP commands to restore them again.

9. 9 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 XCTL Vs LINK Continues... XCTL does not expect control back and hence less overhead on system resources like memory etc. Similar to GO TO. LINK expects control back and hence the overhead is more in this case on memory etc. Similar to perform, and control will be passed back to the instruction following this.

10. 10 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 CALL Vs XCTL/LINK Linkedited along with the main module. Higher module size and higher memory requirement. Single copy can not be used. Separately compiled and link edited. Single copy be shared. Dynamic loading may slow down execution speed.

11. 11 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 CALL Vs XCTL/LINK Continues... Any changes in this require compiling of all other modules using this. A CALLed program remains in the last used state after it returns control. Changes in this will not effect other modules using this. A LINKed or XCTLed program always brings a NEW copy.

12. 12 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 RETURN Return, always passes control back to the program at one logic level higher when used without any options. Return with TRANSID option passes control to another program, in pseudo-conversation mode. It is important to note that RETURN is not at all a replacement for LINK or XCTL.

13. 13 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 ABEND When a situation arises that the program can not handle the program condition, can terminate itself by giving an abend code to help the user. EXEC CICS ABEND ABCODE (‘abcd’) END-EXEC.

14. 14 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 Storage Control GETMAIN - to get main memory FREEMAIN - to release the memory acquired by GETMAIN

15. 15 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 Interval Control ASKTIME FORMATTIME START CANCEL

16. 16 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 Interval Control Continues... START can be used for starting a Transaction from a remote terminal. EXEC CICS START TRANSID (‘TA01’) [INTERVAL (hhmmss)/TIME (hhmmss)] [TERMID (terminal-no)] END-EXEC. CANCEL command can be used to cancel the interval control commands given previously.

17. 17 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 Interval Control Continues... ASKTIME [ABSTIME (data-area)] FORMATTIME ABSTIME (data-value) [YYDDD (data-area)] [YYMMDD (data-area)] [YYDDMM (data-area)] [DDMMYY (data-area)] [MMDDYY (data-area)] [DATE (data-area)] [DATEFORM (data-area)] [DATESEP [(data-area)]] [YEAR (data-area)] [TIME (data-area) [TIMESEP [(data-area)]]

18. 18 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 Summary What are the task control statements and what are they used for? What is the difference between XCTL and LINK? How is CALL different from XCTL and LINK? Why is RETURN used? What are the commands for Storage control? How can we format the date and time from the system?

19. 19 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version No: 1.0 Thank You!