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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).

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Presentation Transcript
slide1

JCL

Day 3

agenda for 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
slide3

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
slide4

VSAM DATASETS (Types)

  • KSDS

Key Sequenced Data Sets

  • ESDS

Entry Sequenced Data Sets

  • RRDS

Relative Record Data Sets

  • LDS

Linear Data Sets

slide5

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

slide6

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)

slide7

(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))

/*

slide8

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)

/*

slide9

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

/*

slide10

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

/*

generation data groups gdgs
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.

slide12

Creating Generation Data Group

1) Create a GDG Base Entry

  • 2) Create a GDG model data set label
  • 3) Create a Generation dataset model
create gdg base entry
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)

/*

creating a model dataset
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

create dscb
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)

create gds generation data set
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

deleting gdg catalog entries
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

/*

listing of gdg catalog information
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

/*

slide19

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.

slide20

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.

review questions
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

review questions1
Review Questions ….
  • What is the limit on the maximum number of generations which can be kept for a GDG?

255

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