VSAM Fundamentals

Course objectives
The students will learn the different Virtual Storage Access Method (VSAM) data set organisations and how to define them for optimum performance.
Making use of practical exercises the students will learn how to invoke IDCAMS services and how to code COBOL VSAM related I/O statements.
The students will learn how to interpret LISTCAT outputs and to identify the necessary tuning actions.

Audience
System programmers, operation analysts and application developers.

Prerequisites
You need a working knowledge of the OS/390 or z/OS environment.

Course contents

Basic I/O concepts

block, logical record

sequential, indexed and direct data processing

access methods

DASD: track, cylinder, access time, ...

Non-VSAM data set organizations and access methods

PS, PDS, IS, DA, and PDSE

BSAM, QSAM, BPAM, ISAM, and BDAM

VSAM record formats

fixed, variable, and spanned

VSAM data set organizations

ESDS, fixed-length RRDS, variable-length RRDS, KSDS, and LDS

VSAM internal organization

CI, CI control information, CA, CI split, CA split, free space, ...

IDCAMS commands

LISTCAT, DEFINE CLUSTER, REPRO, PRINT, DELETE, ALTER, VERIFY, EXAMINE, ...

Defining a VSAM cluster

Loading a VSAM cluster

Interpreting the LISTCAT output

Using COBOL to process ESDS, RRDS, KSDS, KSDS with alternate keys

File status and VSAM codes

Optimizing VSAM performance

space allocation, CI and CA size, free space, index options (IMBED and REPLICATE), buffering, ...

Alternate Indexes, Paths

DEFINE AIX, DEFINE PATH, BLDINDEX commands

Concurrent processing

NSR, LSR and GSR buffering

BLSR subsystem

Hiperbatch

VSAM and SMS

Theoretical and practical exercices