Dummying a dataset with a concatenated list of datasets

15 pts.
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Concatenate
Database
I have an input of 6 contactenated files and I wish to process with just the 4th file in the list. Will dummying the first 3 and last two still pull in the 4th dataset or by dummying the first in the list in effect dummy all of the inputs in the list? Does the dataset you wish to process need to be first in the concat list if you are dummying the rest of them?
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The easiest will be to comment (not DD Dummy) the 5 files that you do not need. DD Dummy may bypass rest of files.
Example:
//SYS040 dd dsn=File4,disp=shr
//* DD DSN=CA.AT880D
//* DD DSN=CA.AT814D
//* DD DSN=CA.AT814D.P090 etc

Let us know if it worked. I am always interested to hear about IBM mainframe, COBOl, JCL, VSAM, etc

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  • carlosdl
    You will need to provide more details. What programs are you using ? Are you developing an application ? if so, what is the programming language ?
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  • Jaharvis
    It is for an existing application. Programming language is COBOL. zOS operation system, MVS JCL. Existing JCL looks like this: //SYS040 DD DSN=CA.AT880D.P010.M05(0),DISP=SHR // DD DSN=CA.AT814D.P020.M01(0),DISP=SHR // DD DSN=CA.AT814D.P090.M01(0),DISP=SHR // DD DSN=CA.AT880d.P010.M06,DISP=SHR // DD DSN=CA.AT880D.P010.M02(0),DISP=SHR // DD DSN=CA.AT880D.P010.M09(0),DISP=SHR We wish to have an additional run of this job, but just pull in the 4th dataset in the list. Currently the programmer has coded the JCL OVERRIDES as follows: //SYS040 DD DUMMY // DD DUMMY // DD DUMMY // DD // DD DUMMY // DD DUMMY I believe that this will dummy out all of the input including the dataset he wants to capture since it is my understanding that when the DUMMY is encountered it set and end of file condition. I believe the JCL override should be coded as follows. //SYS040 DD DSN=CA.AT880D.P010.M06,DISP=SHR // DD DUMMY // DD DUMMY // DD DUMMY // DD DUMMY // DD DUMMY OR //SYS040 DD DSN=CA.AT880D.P010.M06,DISP=SHR // DD DUMMY Any help would be appreciated. Thanks!
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  • InfosysMgmt
    I know this is way late but I would have recommended: 1. Create a new jobstep by copying the step that contains the concatenation. 2. Comment out the orginal jobstep. 3. In the new step, change the name of the DSN on the card bearing the DDName to that of the DSN of the fourth dataset, then remove all other DSN cards in the concatenation. Use the above if you're executing instream JCL. If the JCL shown in your illustration is actually that of a PROC then what I have suggested above will cause an JCL error, instead your JCL would like this: //PROCSTEP EXEC PROCNAME //STEPNAME.SYS040 DD DUMMY // DD DUMMY // DD DUMMY // DD DSN=CA.AT880D.P010.M06,DISP=SHR // DD DUMMY // DD DUMMY
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  • Meandyou
    Jaharvis, I agree with InfoSysMgmt about making the unneeded lines comments. Or just remove the unneeded DD cards. Use of DUMMY as you originally wanted should also work. But this also raises the question of change control for the jobstream. But lets no go down that road at this time. Just remember to CHANGE IT BACK when you are finished.
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  • whatnow
    @Jaharvis:

    What you believed is correct. However, you only need to DD DUMMY once like this:
    //SYS040 DD DSN=CA.AT880D.P010.M06,DISP=SHR
    //              DD DUMMY

    The effect of the override:
    1) the 4th dataset overrides the 1st dataset in the concatenation.
    2) the DD DUMMY overrides the 2nd dataset in the concatenation with a DUMMY dataset, effectively eliminating it and everything else that follows from the concatenation.

    You were also correct that as soon as DD DUMMY is encountered, an End-of-File condition arises. Hence, you only need to code DD DUMMY once.

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