VSAM Programming Course

The course covers, in detail, all aspects of using VSAM and IDCAMS that are important to the senior application COBOL programmer in new system development or maintenance. The class lab is designed to provide an in-depth work experience.

The structure of VSAM will be discussed. Each of the three VSAM file types (KSDS, ESDS, RRDS) will be reviewed in detail showing the design and efficiency features of each. The concepts of Control Area (CA), Control Interval (CI), and other space management features will be covered, as will the features of Alternate Indexing (AIX) and alternate index access PATH (PATH).

All file structures will be related to the MVS/ VSAM space allocation and catalogs necessary to support the files. This includes an introduction of DF/EF and ICF catalogs.

IDCAMS will be fully discussed and used. Creating VSAM files using DEFINE CLUSTER will be described for all file types, as well as other IDCAMS functions of DELETE, PRINT, REPRO, LISTCAT, VERIFY and ALTER.

The workshop application will create fixed and variable length record VSAM files, load the files, create an alternate index and path, and read/insert/delete records using a COBOL program.

The LISTCAT command will be used to review the VSAM catalog information at critical points in the course.

Upon completion of this course, the participant will be able to:
> Discuss the MVS/VSAM catalog facilities
> Discuss how VSAM stores data on disk volumes including Control Intervals / Control Areas
> Discuss the procedures VSAM uses for space management and especially free space
> Create VSAM files
> Create Alternate Indexes, and PATHs
> Manipulate VSAM files using IDCAMS access command of REPRO and PRINT
> Manipulate data in a VSAM file from a COBOL program discuss efficiency features of the three file types

DAY 1
VSAM Structures

I.  INTRODUCTION
A.  Definitions and Concepts
1. Types of datasets  (KSDS, ESDS, RRDS)
2. Alternate Indexes
3. Space management
4. Catalog options
5. Shared datasets

II. DATASET STRUCTURES
A.  ESDS - Entry Sequence Datasets
1. Description
2. Control Interval/Control Areas
3. Design options
> SPANNED and REUSE/NOREUSE
B.  KSDS - Key Sequence Datasets
1. Description

2. Indexes
> Where/how stored Key compression
3. Space management
> Embedded space
> Control Interval splits
> Control Area splits
C. RDS - Relative Record Datasets
1. Description
2. DASD layout
3. Record numbers
D. Alternate Indexes
1. DESCRIPTION
2. DASD layout
3. Paths

DAY 2
III. MVS/VSAM DASD FILE CATALOG AND SPACE MANAGEMENT
A.  File Catalogs - BCS/VVDS
1. Defining the catalogs and Catalog usage
2. UNIQUE/SUBALLOCATION
3. ICF DF/EF logic
4. Using the LISTCAT output listings
B. EXERCISES
1. Review a LISTCAT output

IV.  IDCAMS - ACCESS METHODS SERVICES UTILITY
A. Utility Program Description
B. Define Cluster
C. Other IDCAMS Commands - LISTCAT, ALTER, DELETE, IIERIFY, PRINT, REPRO
D.   WORKSHOP
1. Build KSDS cluster
2. Load cluster with REPRO
3. Print selected data with PRINT
Day 3
IV.  DCAMS - ACCESS METHODS SERVICES UTILITY  (Continued)
E.  Extended IDCAMS Commands
1. Define NONVSAM/Generation Dataset Groups
2. Define ALTERNATEINDEX
a. Review options
b. Upgrade processing
c. Unique/Nonunique Keys
3. BLDINDEX
4. Define PATH

F.   Workshop
1. Create alternate Index
2. Load Alternate Index
3. Print data using the Alternate Index

V. SYSTEM DESIGN AND PERFORMANCE FEATURES
A. Performance Options
1. Index optimization  (IMBED/REPLICATE)
2. Control Interval/Control Area Size selection
3. DASD estimations (FREESPACE/Dataset)
4.  Buffering
B. Shared Datasets
1. MVS JCL
2. SHAREOPTSONS
3. VERIFY
4. Multiple-system environments
C. Performance Guideline Check List
Day 4
VI. COBOL Programming
A.   File Definition – Environment Division
Select statement
File Definition (FD)
Status indicator fields Data Division
Defining key fields
B.   Accessing the File - Procedure Division
OPEN/CLOSE
READ, REWRITE, WRITE, DELETE
Status code checking
Review sample programs
Day 5
VI. COBOL Programming (Continued)
C.  Workshop
1. Code assigned COBOL program
2. Test the program
3. Delete the test files