This is an example of a COBOL program and JCL that will create and process a Generation Data Group or GDG on a Mainframe System with ZOS or a Linux. Generation Data Groups (GDGs) are group of datasets related to each other by a common name. The common name is referred as GDG base and each dataset. JCL & VSAM: Hi all, I want to know the major difference between the dataset and GDG. reagrds akshatha.

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The GV00 has been deleted.

You can specify any no. The purpose of this suite of programs is to provide examples for creating and processing Generation Data Groups GDG’s. GV00, then it leads to changing the JCL every time before execution. In that case, the dataset in the procedure can be overridden in the JCL.

Define a GDG Base. Delete a Generation Data Group. Copyright IBM Corporation If we update this dataset, to create the next generation, the generation number becomes GV Thus, we can access datasets within a GDG in 2 ways: Outdated or obsolete generations can be automatically deleted by the operating system. Software Agreement and Disclaimer.

GDG 0previous versions are referred as -1-2 and so on. The following JCL shows how: Temporary datasets need storage only for the job duration and are deleted at job completion.

Explore the Glossary of Terms for a list of terms and definitions used in this suite of documents and white papers.

In a nutshell, we’ll de-mystify the mainframe. The first group of documents may be available from a local system or via an internet connection, the second group of documents will require an internet connection.

Notice the appended segment of GV00 on the data set name.

In a standardised JCL, the program to be executed mainrrame its related datasets are placed within a cataloged procedure, which is called in the JCL. The preceding job uses the IEFBR14 program a system supplied program that simply does a return to caller with a return code of zero in conjunction with a DD statement to create the model.


Suppose, the Credit Card Accounts have been updated till the month of July.

The following shows the catalog list from Enterprise Server. We have made a significant effort to ensure the documents and software technologies are correct and accurate. Usually, for testing purposes or for an incident fix, there might be a need to use different datasets other than the ones specified in gdh cataloged procedure.

The remaining generation data sets will be retained.

JCL, Execute the Jobs. Suppose we have stored a large amount of data of all credit-card holders in a Sequential Dataset. The SimoTime Home Page. SimoTime Technologies makes no warranty or representations about the suitability of the software, documentation or learning material for any purpose. The function delivered in this version is based upon the enhancement requests from a specific group mwinframe users.

The preceding job that is described in Step 6 created an output file. A good place to start is The SimoTime Home Page for access to white papers, program mainfrqme and product information.

What is GDG Model? To create a GDG Model, we simply need to create an empty dataset, no space allocation, and bearing the DCB of the generations, you want to create. If you have any questions, suggestions, comments or feedback please call or send an e-mail to: If the attributes and organizations of all generations in a group are identical, the generations or individual data sets may be retrieved together as a single data set.

We specialize in preparing applications and the associated mainfrrame that are currently residing on a single platform to be distributed across a variety of platforms. The two zeroes on the end of the name are used to represent a volume number that is used when ggd file is stored on media requiring the use of multiple volumes. I link requires an Internet Connection. Current Server or Internet Access. We reserve the right to make changes without notice at any time.


These tables are provided for individuals that need to better understand the bit structures and differences of the encoding formats.

JCL – Defining Datasets

A typical sequence of events is to submit the jobs described in Steps to Enterprise Server and then review the results. This document and the mainframf to other documents are intended to provide a greater awareness of the Data Management and Application Processing alternatives.

The relative name is a signed integer used to refer to the latest 0the next to the latest -1and so forth, generation. This means, a maximum of 3 generations will be stored in the GDG.

What is a generation data group?

Here, we have kept limit as 3. The Credit-card holders dataset, stores their name, billing address, total credit limit, available balance, minimum amount due etc. Define a GDG Model. How to access a particular generation?

For new non-system-managed data sets, if you do not specify a volume and the data set is not opened, the system does not catalog the data set. If a user has a SimoTime Enterprise License the Documents and Program Suites may be available on a local server and accessed using the icon. New system-managed data sets are always cataloged when allocated, with the volume assigned from a storage group.

An initial model DCB can be defined to be used by all versions, but it can be overridden when creating new versions.