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JCL

JCL. Day 3. Agenda for Day 3. VSAM data sets Definition & Types Record Structure Commands for VSAM files Generation Data Groups Definition JCL’s for GDG’s Storage Management System Definition & requirements. VSAM DATASETS (virtual storage access method).

richard-jefferson
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JCL

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  1. JCL Day 3

  2. Agenda for Day 3 • VSAM data sets • Definition & Types • Record Structure • Commands for VSAM files • Generation Data Groups • Definition • JCL’s for GDG’s • Storage Management System • Definition & requirements

  3. VSAM DATASETS (virtual storage access method) • These are the logical datasets for storing records and are known as clusters. • The term cluster is used because there are two components for many VSAM datasets that are : • Index component - which contains the index • Data component - which contains the actual data

  4. VSAM DATASETS (Types) • KSDS Key Sequenced Data Sets • ESDS Entry Sequenced Data Sets • RRDS Relative Record Data Sets • LDS Linear Data Sets

  5. VSAM DATASETS (KSDS - Key Sequenced Dataset) • These are datasets which are stored in the order of a key field. • The records can be accessed either sequentially or randomly by the record key. • in VSAM as discussed earlier keys are stored separately in an index and the record is accessed in two ways. • First the key in the index is located • Then on the basis of the information stored in the index for that particular key, the record is located

  6. VSAM DATASETS (KSDS - Key Sequenced Dataset) • Vsam stores records in the data component in units called control intervals(CI) Unused Space Control Field Record 2 Record 3 Free space Record 1 CISZ ( CONTROL INTERVAL SIZE)

  7. (KSDS - Key Sequenced Dataset) //ER5077J JOB CLASS=A,NOTIFY=ER4857 //STEP1 EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * DEFINE CLUSTER(NAME(ER5077.VSAM.KSDSFILE) - INDEXED - VOLUME(INUSR2) - RECSZ(80 80) - TRACKS(1 1) - KEYS(4 0) - CISZ(4096) - FREESPACE(3 3)) - DATA - (NAME(ER5077.VSAM.KSDSFILE.DATA)) - INDEX - (NAME(ER5077.VSAM.KSDSFILE.INDEX)) /*

  8. REPRO • REPRO is used to copy VSAM and non VSAM datasets. //ER5077J JOB NOTIFY=&SYSUID //STEP1 EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * REPRO – IDS(ER5077.INPUT.FORVSAM) – ODS(ER5077.VSAM.KSDSFILE) /*

  9. LISTCAT • LISTCAT gives you the catalog information of the cluster //ER5077J JOB ,,CLASS=A,NOTIFY=&SYSUID //STEP1 EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * LISTCAT ENTRY(ER5077.VSAM.KSDSFILE) ALL /*

  10. DELETE • DELETE gives you option to delete the data sets //ER5077J JOB ,,CLASS=A,NOTIFY=&SYSUID //STEP1 EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * DELETE ER5077.VSAM.KSDSFILE /*

  11. Generation Data Groups (GDGs) Processing of a GDG 1) Adding a new generation • 2) Retaining the previous generation • 3) Discarding the oldest generation A Generation Data Group (GDG) is a group of chronologically or functionally related data sets.

  12. Creating Generation Data Group 1) Create a GDG Base Entry • 2) Create a GDG model data set label • 3) Create a Generation dataset model

  13. Create GDG base entry Create an index for the GDG //ER5077J JOB ,,NOTIFY=&SYSUID,CLASS=A //STEP1 EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * DEFINE GDG - (NAME(ER5077.PAY.ROLL) - LIMIT(3) - EMPTY - SCRATCH) /*

  14. Creating a model dataset For Non SMS managed datasets, define a model dataset (DSCB) such that new GDG created will use prespecified parameters DSCB supplies the DCB &EXPDT subparameters for the GDG The model dataset must be cataloged It is linked to the GDG via a “DCB=model name” on creating new GDG’s

  15. Create DSCB //ER5077J JOB ,,NOTIFY=&SYSUID,CLASS=A //STEP1 EXEC PGM=IEFBR14 //DD1 DD DSN=ER5077.PAYROLL,DISP=(,KEEP), // SPACE=(TRK,(0)),VOL=SER=,UNIT=SYSDA, // DCB=(RECFM=FB,LRECL=80,BLKSIZE=800)

  16. Create GDS(generation data set) //ER5077J JOB ,,NOTIFY=&SYSUID,CLASS=A //STEP1 EXEC PGM=IEFBR14 //DD1 DD DSN=ER5077.PAY.ROLL (+1), // DISP=(NEW,CATLG), // SPACE=(TRK,(1,1)), // UNIT=SYSDA, // DCB=ER5077.PAYROLL

  17. Deleting GDG Catalog Entries • Delete a model //ER5077J JOB ,,NOTIFY=&SYSUID,CLASS=A //STEP1 EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * DELETE ER5077.PAYROLL PURGE /* • Delete an allocated GDG and deletes all GDS’s //ER5077J JOB ,,NOTIFY=&SYSUID,CLASS=A //STEP1 EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * DELETE ER5077J.PAY.ROLL PURGE FORCE /*

  18. Listing of GDG Catalog Information //ER5077J JOB ,,NOTIFY=&SYSUID,CLASS=A //STEP1 EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * LISTCAT GDG ENTRIES(ER5077J.PAY.ROLL)ALL /*

  19. SMS (Storage Management Subsystem) • SMS is an optional feature of MVS. • It is a tool that is used to improve the management of available disk space. • Data sets created under SMS are known as SMS managed datasets . • PDS are known as PDSE when converted to SMS managed datasets can be done by IEBCOPY. Under SMS while creating a dataset you need to specify : - STORCLAS instead of UNIT - DATACLAS instead of DCB& SPACE - MGMTCLAS for migration of datasets.

  20. SMS (Storage Management Subsystem) • Generally, your existing JCL will continue to execute correctly. • SMS allows the installation to benefit from the data class, management class, and storage class constructs without changing existing JCL. • The installation-written ACS routines can be designed to filter existing parameters on the DD statement and select appropriate constructs for the data set.

  21. Review Questions • What are the different types of VSAM files? KSDS, ESDS, RRDS, LDS • VSAM stores records in the data component in units called _______ Control intervals • When we are using GDG’s then what do following versions mean in a JCL? (-1), (+0) & (+1). -1 – Version of data set previous to current existing +0 – Current existing version of data set +1 – New version of data set getting created

  22. Review Questions …. • What is the limit on the maximum number of generations which can be kept for a GDG? 255

  23. Thank You!

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