VSAM

INTRODUCTION

VSAM stands for Virtual Storage Access Method, is IBM high performance access method which allows you to access files of different organization such as sequential, indexed, relative record and linear datasets.

Features of VSAM

VSAM is one coherent file storage system used to store and retrieve data. It is not a database management system like IDMS or DB2. It does not provide for relationships among the data. The existing databases like IMS or DB2 may be implemented using VSAM.
VSAM is not a programming language. But you can access VSAM dataset through programming languages like COBOL or PL/I. It is not a communication system like VTAM or CICS. It has no equivalent for a ‘PDS’ type of file organization.

Advantages of VSAM

Provides protection of Data against unauthorized access through password facility.

Cross-system (MVS & VSE) Compatibility.  VSAM datasets can be imported and imported in MVS and VSE systems.

Device Independence (Access Via Catalog).  The application programmer need not be concerned with Block size ,volume and other  control information, as access to VSAM dataset it always through the Catalog and all control information are stored in the catalog entry of the dataset.

IDCAMS commands can be included in JCL to handle VSAM datasets

NOTE: Click the Chapter Name for More information.

CHAPTER 1. BASIC CONCEPTS

CHAPTER 2. VSAM CATALOGS.

CHAPTER 3. VSAM DATASETS

CHAPTER 4. CLUSTERS

CHAPTER 5. IDCAM COMMANDS.

CHAPTER 6. ALTERNATE INDEX

CHAPTER 7. ADDITIONAL VSAM COMMANDS.

CHAPTER 8. VSAM STATUS CODES.

CHAPTER 9. VSAM PROGRAMS.

CHAPTER 10. FAQ's  ON VSAM.