MVSFORUMS.com

[javedsk12]

please can sombody put some light on PCB mask what it is ??? i have gone through the manuals but not getting it can somebody put it in simple words??
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javed

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The Word Impossible it self says i am possible(im possible)

[kolusu]

javedsk12,

In simple terms a PCB MASK is used to determine what happened when the IMS call is completed. The result of each call in IMS is shown in the mask of the PCB being used. The mask contains about 9 fields (If I remember correctly) which contains the Database name ,segment name and status code of the call. So after every call you can check status code field defined in the mask.
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Kolusu
www.linkedin.com/in/kolusu

[javedsk12]

suppose i am having the table emp with fields name,age,salary

name age salary

jhon 21 30000
sam 22 40000
ryan 25 50000

and i am putting the query like this,

select name from emp where name='jhon'

in this total ex what is my pcb,psb,dbd,ssa and pcb mask please can anybody put light on this.
_________________
javed

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The Word Impossible it self says i am possible(im possible)

[javedsk12]

again segment for the same example
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javed

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The Word Impossible it self says i am possible(im possible)

[Nic Clouston]

A PCB mask is used with IMS - you are using DB2 so a PCB mask is not used. PSBs,DBDs and SSAs are all IMS terms - not DB2. I susggest you read the IMS manuals - start with "Application Programming - IMS DB" from the links in the "Quick Manuals" link at the top of this web page.
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Utility and Program control cards are NOT, repeat NOT, JCL.

[rk_pulikonda]

It is not as simple to compare IMS(hierachial) with DB2(relational) databases.

DBD:
One or more segments connected with parent/child relation. Each segment is called a Table or entire DBD also you can assume as a table.

PSB:
If you want to read the data from more than one table you will create a view in DB2.
If a program want to access the view you will have a plan for each program.
Similarly in IMS you will have PSB for each program to access different databases(DBD).When you
access Database(DBD) you can access all the fields/some fields from each database(DBD) similar to view.
PCB will be connected to each DBD defined in PSB.

If you see in your PSB defenition you will see PCB entries for each DBD.

PCB Mask:
Before IMS sends control to your program it will read your PSB.If your PSB defined with two DBD which means your program
wants to access two databases. There will a PCB attach to each DBD. IMS will send address of each DBD through PCB to your program
as if you are sending data to a subprogram.

Generally in your IMS program procedure division may be any of the below types.

PROCEDURE DIVISION USING PCB-EMPLOYEE
PCB-DEPT
OR
PROCEDURE DIVISION
ENTRY 'DLITCBL' USING PCB-EMPLOYEE
PCB-DEPT

In batch IMS(DFSRRc00) is the main program and your program is subprogram to it. When IMS sends address of your two databases to your program
PCB-EMPLOYEE/PCB-DEPT will be received in the same order as defined in PSB. These masks are defined in Linkage section because your program is subprogram to IMS program.

Using PCB-EMPLOYEE mask you will read/update the Employee database same thing for dept mask.


SSA:
Similar to your where clause in DB2


Not sure how far it is useful...
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Thanks
-Ram

[javedsk12]

Thanks Ram for your valuable inputs on the topic
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javed

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The Word Impossible it self says i am possible(im possible)