Logo

Navigation
  • Home
  • Services
    • ERP Solutions
    • Implementation Solutions
    • Support and Maintenance Solutions
    • Custom Solutions
    • Upgrade Solutions
    • Training and Mentoring
    • Web Solutions
    • Production Support
    • Architecture Designing
    • Independent Validation and Testing Services
    • Infrastructure Management
  • Expertise
    • Microsoft Development Expertise
    • Mobile Development
    • SQL Server Database and BI
    • SAP BI, SAP Hana, SAP BO
    • Oracle and BI
    • Oracle RAC
  • Technical Training
    • Learn Data Management
      • Business Intelligence
      • Data Mining
      • Data Modeling
      • Data Warehousing
      • Disaster Recovery
    • Learn Concepts
      • Application Development
      • Client Server
      • Cloud Computing Tutorials
      • Cluster Computing
      • CRM Tutorial
      • EDI Tutorials
      • ERP Tutorials
      • NLP
      • OOPS
      • Concepts
      • SOA Tutorial
      • Supply Chain
      • Technology Trends
      • UML
      • Virtualization
      • Web 2.0
    • Learn Java
      • JavaScript Tutorial
      • JSP Tutorials
      • J2EE
    • Learn Microsoft
      • MSAS
      • ASP.NET
      • ASP.NET 2.0
      • C Sharp
      • MS Project Training
      • Silverlight
      • SQL Server 2005
      • VB.NET 2005
    • Learn Networking
      • Networking
      • Wireless
    • Learn Oracle
      • Oracle 10g
      • PL/SQL
      • Oracle 11g Tutorials
      • Oracle 9i
      • Oracle Apps
    • Learn Programming
      • Ajax Tutorial
      • C Language
      • C++ Tutorials
      • CSS Tutorial
      • CSS3 Tutorial
      • JavaScript Tutorial
      • jQuery Tutorial
      • MainFrame
      • PHP Tutorial
      • VBScript Tutorial
      • XML Tutorial
    • Learn Software Testing
      • Software Testing Types
      • SQA
      • Testing
  • Career Training
    • Career Improvement
      • Career Articles
      • Certification Articles
      • Conflict Management
      • Core Skills
      • Decision Making
      • Entrepreneurship
      • Goal Setting
      • Life Skills
      • Performance Development
      • Personal Excellence
      • Personality Development
      • Problem Solving
      • Relationship Management
      • Self Confidence
      • Self Supervision
      • Social Networking
      • Strategic Planning
      • Time Management
    • Education Help
      • Career Tracks
      • Essay Writing
      • Internship Tips
      • Online Education
      • Scholarships
      • Student Loans
    • Managerial Skills
      • Business Communication
      • Business Networking
      • Facilitator Skills
      • Managing Change
      • Marketing Management
      • Meeting Management
      • Process Management
      • Project Management
      • Project Management Life Cycle
      • Project Management Process
      • Project Risk Management
      • Relationship Management
      • Task Management
      • Team Building
      • Virtual Team Management
    • Essential Life Skills
      • Anger Management
      • Anxiety Management
      • Attitude Development
      • Coaching and Mentoring
      • Emotional Intelligence
      • Stress Management
      • Positive Thinking
    • Communication Skills
      • Conversation Skills
      • Cross Culture Competence
      • English Vocabulary
      • Listening Skills
      • Public Speaking Skills
      • Questioning Skills
    • Soft Skills
      • Assertive Skills
      • Influence Skills
      • Leadership Skills
      • Memory Skills
      • People Skills
      • Presentation Skills
    • Finding a Job
      • Etiquette Tips
      • Group Discussions
      • HR Interviews
      • Interview Notes
      • Job Search Tips
      • Resume Tips
      • Sample Resumes
 

VSAM Catalogs

By Exforsys | on June 20, 2007 |
MainFrame

VSAM Catalogs

In this Mainframe tutorial, you will learn about VSAM Catalogs, Master Catalog, User Catalog and Data Space of VSAM.

Master Catalog

Master Catalog in VSAM is like captain of a ship, since all files used in VSAM is controlled by this master catalog. The attributes of files like password authorization for files, monitoring of operation performed on files, VSAM access for files, location of the file, space management of file, available free space in file are all monitored, managed and present in Master catalog. The above attributes are maintained and updated as and when the attributes of files changes like if the file gets updated, file expands in size and file size gets reduced keeping the master catalog always updated with current information and attributes of file.

There are many operations of the file during which the master catalogue is referred by VSAM for security. For instance one could be when a requested file is opened and closed. In this process of opening and closing the requested file the appropriate password is requested to the user and VSAM checks the associated master catalog entry for password verification before proceeding with the operations requested on the file, thereby enhancing the security. A vital point one must know is, the Master Catalog by itself is a file. The entries in this master catalog file would be system datasets and VSAM structures. All these help in monitoring and management operations of VSAM. The master catalog is defined using IDCAMS program. There would be only one master catalog for a VSAM system.

User Catalog

The User Catalog is present at the lower hierarchy of the Master Catalog and has the same structure and concepts as the master catalog. It is not that user catalogue must be made mandatory as master catalog but if present it would enhance the security of VSAM system. We saw in our earlier master catalog explanation that master catalog by itself is a file and would point to other files. But if user catalogues are defined master catalog would point to user catalog instead of pointing to VSAM files and these user catalogs would in turn point to VSAM files.

As we have seen before there would be only one master catalog for a VSAM system. But in contrast it is possible that a user catalog can be present in any number as needed for instance as in a production system which might have any number of user catalog as needed by the system. Also the structure of VSAM is such a way that even when the master catalog is destroyed, the user catalogs are not affected. Also even if the user catalog is destroyed only the files under that catalog will get destroyed, which enables rebuilding the catalog without much process and work on other files.

Master Catalog hierarchy is depicted in diagram below:

 

When a VSAM structure has user catalog and master catalog as shown above in the diagram then the request for a file would pass through different hierarchy as explained below. The file request will first pass through the master catalog, then through the user catalog present below the master catalogue and finally finish up on the third stage at the appropriate file.

VSAM Data Space

The data space is an area of the direct access storage device volume which is used by VSAM and hence called as VSAM data space. The data space need not occupy the entire volume of the direct access storage device volume. It is possible that it may occupy only a portion of the volume of direct access storage device volume or may occupy it fully as specified. For specifying this space allocation it must be defined in the catalog. Once the space occupation is specified in the catalog the VSAM takes control of this space and monitors and maintains this space as needed by VSAM files. This space must also be defined in the VTOC. The main difference in the name entry between VTOC and catalogue entry of files is that in case of VSAM catalog individual files will appear whereas in case of VTOC only the name given to the area of the entire VSAM data space will appear. In other words VTOC has entry of area occupied by space.

Defining of master catalog or a user catalog enables VSAM create a data space to hold the user catalog entries. In this allocation of the amount of space specified for the user catalog from the space available on the volume as a data space is made.  

The relationship between the different VSAM catalogs is that, Master Catalog should contain pointers to the User Catalogs which is present in a lower hierarchy to the master catalog. Also all data sets cataloged in the user catalog should have a higher level qualifier equal to the name of the user catalog.

« « Data Modeling Introduction
Connection between Data Model and Data Warehouse » »

Author Description

Avatar

Editorial Team at Exforsys is a team of IT Consulting and Training team led by Chandra Vennapoosa.

Free Training

RSSSubscribe 392 Followers
  • Popular
  • Recent
  • Introduction to JCL

    November 8, 2006 - 0 Comment
  • Customer Information Control System (CICS)

    July 25, 2006 - 0 Comment
  • Mainframes Computers

    May 27, 2007 - 0 Comment
  • Mainframe Features

    June 17, 2007 - 0 Comment
  • VSAM Introduction

    June 18, 2007 - 0 Comment
  • VSAM Structure

    June 21, 2007 - 0 Comment
  • VSAM Control Interval and Control Area

    June 23, 2007 - 0 Comment
  • JES : Job Entry Subsystem

    June 26, 2007 - 0 Comment
  • CICS Overview and Functions

    June 18, 2006 - 0 Comment
  • CICS Components and Transactions

    June 18, 2006 - 0 Comment
  • JES : Job Entry Subsystem

    June 26, 2007 - 0 Comment
  • VSAM Control Interval and Control Area

    June 23, 2007 - 0 Comment
  • VSAM Structure

    June 21, 2007 - 0 Comment
  • VSAM Introduction

    June 18, 2007 - 0 Comment
  • Mainframe Features

    June 17, 2007 - 0 Comment
  • Mainframes Computers

    May 27, 2007 - 0 Comment
  • Introduction to JCL

    November 8, 2006 - 0 Comment
  • Customer Information Control System (CICS)

    July 25, 2006 - 0 Comment
  • CICS Components and Transactions

    June 18, 2006 - 0 Comment
  • CICS Overview and Functions

    June 18, 2006 - 0 Comment

Exforsys e-Newsletter

ebook
 

Related Articles

  • JES : Job Entry Subsystem
  • VSAM Control Interval and Control Area
  • VSAM Structure
  • VSAM Introduction
  • Mainframe Features

Latest Articles

  • Project Management Techniques
  • Product Development Best Practices
  • Importance of Quality Data Management
  • How to Maximize Quality Assurance
  • Utilizing Effective Quality Assurance Strategies
  • Sitemap
  • Privacy Policy
  • DMCA
  • Trademark Information
  • Contact Us
© 2023. All Rights Reserved.IT Training and Consulting
This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish.AcceptReject Read More
Privacy & Cookies Policy

Privacy Overview

This website uses cookies to improve your experience while you navigate through the website. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may affect your browsing experience.
Necessary
Always Enabled
Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
Non-necessary
Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.
SAVE & ACCEPT