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VSAM Demystified

Book Description

Virtual Storage Access Method (VSAM) is one of the access methods used to process data. Many of us have used VSAM and work with VSAM data sets daily, but exactly how it works and why we use it instead of another access method is a mystery.

This book helps to demystify VSAM and gives you the information necessary to understand, evaluate, and use VSAM properly. It clarifies VSAM functions for application programmers who work with VSAM. The practical, straightforward approach should dispel much of the complexity associated with VSAM. Wherever possible an example is used to reinforce a description of a VSAM function.

This IBM Redbook is intended as a supplement to existing product manuals. It is intended to be used as an initial point of reference for VSAM functions.

This book also builds upon the subject of Record Level Sharing and the new z/OS feature called DFSMStvs.

Table of Contents

  1. Copyright
  2. Figures
  3. Tables
  4. Preface
  5. VSAM basics
    1. A brief description of VSAM
    2. VSAM functions by release level
    3. What is VSAM?
    4. Major VSAM parts
    5. VSAM terminology and concepts
    6. VSAM data set organizations
    7. Comparing VSAM data set organizations
    8. Choosing a VSAM data set type
    9. Extended format data set
    10. Extended addressability
    11. Data striping
    12. Processing a VSAM cluster
    13. VSAM exploiters
  6. Performance
    1. Service level agreement
    2. Transaction performance
    3. Performance management
    4. VSAM performance management
    5. VSAM rule-of-thumb mode
    6. Parameters affecting performance
    7. VSAM performance by scenarios
    8. VSAM and ESS controllers
    9. Performance monitors
  7. VSAM problem determination and recovery
    1. VSAM problem determination hints and tips
    2. Some common VSAM problems
    3. What documentation to collect
    4. How to recover a damaged VSAM data set
    5. Prevention is better than cure
    6. Where to look for more information
    7. IDC3009I message
    8. IDCAMS LISTCAT output fields
    9. SMF record types related to VSAM data sets
    10. RRMS and VSAM
  8. Managing your VSAM data sets
    1. Reorganization considerations
    2. New Index CI size calculation algorithm
    3. Sharing VSAM data sets
    4. Extended addressability (EA)
    5. Catalog Search Interface
    6. Major sources of VSAM processing options
    7. Media Manager, Open, Close, EOV in VSAM
    8. VSAM and 64 bits
    9. Special considerations for COBOL users and SMB
  9. VSAM Record Level Sharing
    1. Introducing VSAM RLS
    2. RLS terminology
    3. Planning for RLS
    4. Implementing VSAM RLS
    5. RLS problem determination and recovery
    6. RLS enhancements
    7. RLS performance
  10. DFSMStvs
    1. Introducing DFSMStvs
    2. Why DFSMStvs?
    3. Some definitions
    4. CICS support for recoverable VSAM
    5. DFSMStvs overview
    6. Our experiences with implementation
    7. DFSMStvs problem determination tips
  11. Sample code
    1. JRIO API examples
    2. Accessing the VSAM Shared Information (VSI)
    3. Sample programs extract from SMF record type 64
    4. REXX code to list compression ratio
    5. GTF procedure example
  12. Miscellaneous performance items
    1. Our test environment
    2. Hardware configuration
    3. Software configuration
    4. General lab description
    5. Share options analogy
    6. Symptoms (messages) from a broken data set
    7. IDCAMS EXAMINE messages
  13. Catalog performance
    1. Performance
    2. Enhanced Catalog Sharing
    3. GRS configuration
    4. Diagnosing prolonged catalog ENQ times
  14. Information APARs
    1. II12927 - Documentation for VSAM problems
    2. II13326 - Common problems with SHCDS
    3. BDC000010564
    4. BDC000007033
    5. II12603
    6. II12243
    7. BDC000022923
    8. RTA000141603
  15. Glossary
  16. Related publications
    1. IBM Redbooks
    2. Other publications
    3. Online resources
    4. How to get IBM Redbooks
    5. Help from IBM
  17. Back cover
  18. Index