Control Operations Day 5. 2 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version...
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Transcript of Control Operations Day 5. 2 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/TP01/003 Version...
Control OperationsDay 5
2Copyright © 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
3Copyright © 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 taskENQ
RESOURCE (data-area)
[LENGTH (data-value)]
[NOSUSPEND]
Conditions: ENQBUSY, LENGERR
DEQ RESOURCE (data-area)
[LENGTH (data-value)]
Conditions: LENGERR
4Copyright © 2005, Infosys Technologies Ltd
ER/CORP/CRS/TP01/003 Version No: 1.0
Program Control Commands• XCTL
• LINK
• RETURN
• ABEND
• LOAD
• RELEASE
5Copyright © 2005, Infosys Technologies Ltd
ER/CORP/CRS/TP01/003 Version No: 1.0
Logic Levels
CICS
PGM ALINK BRETURN
PGM CLINK DRETURN
PGM BXCTL C
PGM DRETURN
LEVEL 0
LEVEL 1
LEVEL 2
LEVEL 3
CICS
PGM ALINK BRETURN
PGM CLINK DRETURN
PGM BXCTL C
PGM DRETURN
LEVEL 0
LEVEL 1
LEVEL 2
LEVEL 3
6Copyright © 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.
7Copyright © 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.
8Copyright © 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.
9Copyright © 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.
10Copyright © 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.
11Copyright © 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.
12Copyright © 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.
13Copyright © 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.
14Copyright © 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
15Copyright © 2005, Infosys Technologies Ltd
ER/CORP/CRS/TP01/003 Version No: 1.0
Interval Control
• ASKTIME
• FORMATTIME
• START
• CANCEL
16Copyright © 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.
17Copyright © 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)]]
18Copyright © 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?
19Copyright © 2005, Infosys Technologies Ltd
ER/CORP/CRS/TP01/003 Version No: 1.0
Thank You!