JCL
DAY 4
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VSAM DATASETS
(virtual storage access method)
• These are the logical dataset 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
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VSAM DATASETS
(virtual storage access method)
VSAM is a
•
High performance access method and data set Organization.
•
Provides data security and Integrity.
•
Shares Buffers and control blocks among VSAM data sets.
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VSAM DATASETS
(virtual storage access method)
TYPES OF VSAM Data sets.
• Key sequenced Datasets.
• Entry sequence Data sets.
• Relative record data sets.
• Linear Data sets.
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VSAM DATASETS
(virtual storage access method)
Key Sequence Data sets.
• Records are places in an ascending order.
• The key must be unique.
• The position of the key should be same in all records.
• Records can be retrieved either Randomly or Sequentially.
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VSAM DATASETS
(virtual storage access method)
Entry Sequence Data sets.
• Records are either placed or accessed in the order of
their entry.
• Records are sequentially accessed or by RBA concept.
( RBA – Relative Byte address )
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VSAM DATASETS
Relative Record Data sets.
( RRDS )
• Pre defined slots to accommodate the data.
• Each slot carries a Relative record number ( RRN ) with
respect to the first record.
• Records are read with the help of the RRN.
• Records are sequentially accessed or by RBA concept.
( RBA – Relative Byte address )
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VSAM DATASETS
(KSDS - Key Sequenced Dataset)
• Vsam stores records in the data component in units called
control intervals(CI)
Unused Space
Control Field
Record 1
Record 2
Record 3
Free space
CISZ
( CONTROL INTERVAL SIZE)
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VSAM UTILITY
IDCAMS
( IDC Access Method Services )
The Functions of IDCAMS are as follows.
•
•
•
•
•
•
Define
Repro ( Copy )
List
Print
Verify
Delete
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(KSDS - Key Sequenced Dataset)
DEFINE
000100 //INF6244A JOB CLASS=A,NOTIFY=INF6244
000200 //STEP1 EXEC PGM=IDCAMS
000300 //SYSPRINT DD SYSOUT=*
000400 //SYSIN DD *
000500 DEFINE CLUSTER(NAME(ER24172.VSAM.KSDS1) 000600 INDEXED
000700 VOLUME(SMS008)
000800 RECSZ(80 80)
000900 TRACKS(1 1)
001000 KEYS(4 0)
001010 CISZ(4096)
001100 FREESPACE(3 3))
001101
DATA
001110
(NAME(ER24172.VSAM.KSDS1.INDEX))
001111
INDEX
001120
(NAME(ER24172.VSAM.KSDS1.DATA)
001200 )
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001700 /*
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(KSDS - Key Sequenced Dataset)
(using repro)
• REPRO is used to copy VSAM and non VSAM datasets.
000100 //INF6244A JOB NOTIFY=INF6244
000200 //STEP1 EXEC PGM=IDCAMS
000300 //SYSPRINT DD SYSOUT=*
000400 //SYSIN DD *
000410 REPRO
000500 IDS(INF6244.INPUT.JCLPS1) 000600 ODS(INF6244.VSAM.KSDS1)
000700 /*
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(KSDS - Key Sequenced Dataset)
(using listcat)
• LISTCAT gives you the catalog information of the cluster
000100 //INF6244A JOB CLASS=A,NOTIFY=INF6244
000200 //STEP1 EXEC PGM=IDCAMS
000300 //SYSPRINT DD SYSOUT=*
000400 //SYSIN DD *
000500 LISTCAT ENTRY(INF6244.VSAM.KSDS1) ALL
000600 /*
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(KSDS - Key Sequenced Dataset)
(delete)
000100 //INF6244A JOB CLASS=A,NOTIFY=INF6244
000200 //STEP1 EXEC PGM=IDCAMS
000300 //SYSPRINT DD SYSOUT=*
000400 //SYSIN DD *
000500 DELETE INF6244.VSAM.KSDS1
001106 /*
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Generation Data Groups (GDGs)
A Generation Data Group (GDG) is a group of chronologically or
functionally related data sets.
Processing of GDG
1) Adding a new generation
2) Retaining the previous generation
3) Discarding the oldest generation
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Creating Generation Data Group
1) Create a GDG Base Entry
2) Create a GDG model data set label
3) Create a Generation dataset model
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Create GDG base entry
Create an index for the GDG
000100 //INF62441 JOB (AMLAN),NOTIFY=INF6244,CLASS=A
000200 //STEP1 EXEC PGM=IDCAMS
000300 //SYSPRINT DD SYSOUT=*
000400 //SYSIN DD *
000500 DEFINE GDG 000600 (NAME(INF6244.PAYROLL.VERSION)000700 LIMIT(3)000800 EMPTY000900 SCRATCH)
001000 /*
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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 GDS
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Create DSCB
000100 //INF62441 JOB (AMLAN),NOTIFY=INF6244,CLASS=A
000200 //STEP1 EXEC PGM=IEFBR14
000600 //DD1 DD DSN=INF6244.PAYROLL,DISP=(,KEEP),
000700 //
SPACE=(TRK,(0)),VOL=SER=,UNIT=SYSDA,
000800 //
DCB=(RECFM=FB,LRECL=80,BLKSIZE=800)
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Create GDS
(generation data set)
000100 //INF62441 JOB (AMLAN),NOTIFY=INF6244,CLASS=A
000200 //STEP1 EXEC PGM=IEFBR14
000300 //DD1 DD DSN=INF6244.PAYROLL.VERSION(+1),DISP=(NEW,CATLG),
000400 //
SPACE=(TRK,(1,1)),VOL=SER=,UNIT=SYSDA,
000500 //
DCB=INF6244.PAYROLL
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Deleting GDG Catalog Entries
•Delete a model
000100 //INF62441 JOB (AMLAN),NOTIFY=INF6244,CLASS=A
000200 //STEP1 EXEC PGM=IDCAMS
000300 //SYSPRINT DD SYSOUT=*
000400 //SYSIN DD *
000500 DELETE INF6244.PAYROLL PURGE
000600 /*
•Delete an allocated GDG and deletes all GDS’s
000100 //INF62441 JOB (AMLAN),NOTIFY=INF6244,CLASS=A
000200 //STEP1 EXEC PGM=IDCAMS
000300 //SYSPRINT DD SYSOUT=*
000400 //SYSIN DD *
000500 DELETE INF6244.PAYROLL.VERSION PURGE FORCE
000600 /*
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Listing of GDG Catalog Information
000100 //INF62441 JOB (AMLAN),NOTIFY=INF6244,CLASS=A
000200 //STEP1 EXEC PGM=IDCAMS
000300 //SYSPRINT DD SYSOUT=*
000400 //SYSIN DD *
000500 LISTCAT GDG ENTRIES(INF6244.PAYROLL.VERSION)ALL
000600 /*
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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.
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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.
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That is the end of JCL course
Thank you
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