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Prabha
Warnings : 2
New User
Joined: 05 Dec 2005
Posts: 79
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Hi,
Can anyone explain me the usage of static varible. Is static varible is only for storage purpose or to keep value. Please explain me with examples. I searched in other forums. But it was not clear. |
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CICS Guy
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Joined: 18 Jul 2007
Posts: 2146
Location: At my coffee table
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| Can you provide a link to where you found a reference to the term static variable? |
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Phrzby Phil
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Joined: 31 Oct 2006
Posts: 1042
Location: Richmond, Virginia
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In your terms, what is the difference between "storage purposes" and "keep a value"?
STATIC vars are a PL/I concept. From a web-link:
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| Storage. PL/I provides a number of storage attributes. The default is AUTOMATIC, which is allocated on entry to a block, possibly with initialization, and freed at exit. STATIC storage exists throughout the life of the program, |
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ruodeer
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Joined: 06 Jul 2007
Posts: 58
Location: home
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| as saying:static for batch program..automatic for online program. |
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Bill O'Boyle
CICS Moderator
Joined: 14 Jan 2008
Posts: 2501
Location: Atlanta, Georgia, USA
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Do you mean an Assembler constant (DC)?
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EYECTCHR DC CL38'HELLO, I AM A CONSTANT, LEAVE ME ALONE'
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HTH....
Regards,
Bill |
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u770624
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Joined: 12 Jul 2006
Posts: 2
Location: Blighty
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Illustration on use of static variables ...
Module_A calls Module_B ( and it can do so many times )
Module_B needs to know when it is called for the first time (probably as an efficiency measure)
Therefore Module_B declares a STATIC variable and initialises it to a known value.
Module_B checks the static variable every time it is called and if it is the known, initiallised value then it is the first time it is called. Module_B then performs the first time logic AND sets the static variable to a different value.
On subsequent calls, the value is no longer the initiallised value.
If it was not a static variable then it would be a dynamic variable and would be set to the initiallised value every time Module_B was called. |
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Mistermind
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Joined: 08 Feb 2008
Posts: 46
Location: Dublin
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Static storage is mapped just once inside the PL/I loadmodule, similar to WORKING-STORAGE variable in cobol. Automatic variables are allocated new storage space each time you invoke the subroutine B, so if your subroutine B declares AUTO variables, your partition will very quickly run out of space. This problem will not arise if STATIC variable is declared. If subroutine needs to ensure a certain value in a static variable, e.g. zero, it can be set each time subroutine gains control.
PL/I STATIC variables are also easier to find in storage, always addressed by register 3. |
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