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VSAM - How do you define a KSDS ?




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asked mar August 7, 2014 12:44 PM  

How do you define a KSDS ?


           

1 Answers



 
answered By Mswami   0  
KSDS Cluster Components:

Each record in the data component of a KSDS cluster contains a key field, which must be the same number of characters and occur in the same relative position in each record.  The records are stored in the data component in logical sequence based upon their key field value.  The index component of the KSDS cluster contains the list of key values for the records in the cluster with pointers to the corresponding records in the data component.  The records in a KSDS may be accessed sequentially, in order by key value, or directly, by supplying the key value of the desired record.  The records of a KSDS cluster may be fixed length or variable length.  Records may be added or deleted at any point within a KSDS cluster, and the affected record is inserted or removed, and the surrounding records will be reorganized as required to maintain the correct logical sequence.

Examples:

The following jobstream will define a Key Sequenced cluster.

//DEFCLUSK JOB 'JAY MOSELEY',CLASS=A,MSGLEVEL=(1,1),MSGCLASS=A
//IDCAMS EXEC PGM=IDCAMS,REGION=4096K            
//SYSPRINT DD SYSOUT=A                    
//SYSIN  DD *                       
                               
 /* DELETE KSDS CLUSTER, IF IT EXISTS           */
                               
 DELETE MVS801.STUDENT.FILE CLUSTER PURGE          
                               
 /* DEFINE KSDS CLUSTER                  */
                               
 DEFINE CLUSTER (                     - 
        NAME(MVS801.STUDENT.FILE)          - 
        VOLUMES(MVS801)               - 
        RECORDSIZE(80 80)              - 
        RECORDS(50 10)                - 
        KEYS(10 0)                  - 
        INDEXED )                  - 
     DATA (                       - 
        NAME(MVS801.STUDENT.FILE.DATA) )       - 
     INDEX (                      - 
        NAME(MVS801.STUDENT.FILE.INDEX) )       
                               
 IF LASTCC = 0 THEN                    - 
    LISTCAT ALL LEVEL(MVS801.STUDENT)           
                               
/*                              
//                              



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