What is VTOC index?
The VTOC index is a physical-sequential data set on the same volume as the related VTOC. It consists of an index of data set names in DSCBs contained in the VTOC and volume free space information. The data set names are in format-1 and format-8 DSCBs.
What is a VTOC in mainframe?
In the IBM System/360 storage architecture, the Volume Table of Contents (VTOC), is a data structure that provides a way of locating the data sets that reside on a particular DASD volume. It lists the names of each data set on the volume as well as size, location, and permissions.
How is VTOC used in mainframe?
The VTOC lists the data sets that reside on its volume, along with information about the location and size of each data set, and other data set attributes. A standard z/OS utility program, ICKDSF, is used to create the label and VTOC. More data sets on the disk volume require more space in the VTOC.
What is the latest version of z OS?
2.5
z/OS is a 64-bit operating system for IBM z/Architecture mainframes, introduced by IBM in October 2000….This article’s tone or style may not reflect the encyclopedic tone used on Wikipedia.
| Developer | IBM |
|---|---|
| Latest release | Version 2.5 (V2R5) / September 30, 2021 |
Are mainframes still used?
Despite predictions of its demise at the hands of cloud, mainframe is still widely used. Indeed, mainframe technology has evolved greatly in the five decades since it first appeared and many organisations, including 70% of Fortune 500 businesses, are still using mainframe systems to power core business operations.
What is Z OS designed for?
z/OS®, a widely used mainframe operating system, is designed to offer a stable, secure, and continuously available environment for applications running on the mainframe. z/OS today is the result of decades of technological advancement.
What is DCB in JCL?
DCB. The Data Control Block (DCB) parameter details the physical characteristics of a dataset. This parameter is required for datasets that are newly created in the job step. LRECL is the length of each record held within the dataset. RECFM is the record format of the dataset.
What is volume in JCL?
VOLUME parameter used to identify the volume(s) on which the dataset resides or will reside. The volume request for new datasets can be private volume, retention of the volume, volume by serial number or the volume that other datasets uses. VOLUME is optional parameter.
Why is mainframe still used?
Businesses today rely on the mainframe to: Perform large-scale transaction processing (thousands of transactions per second) Support thousands of users and application programs concurrently accessing numerous resources. Manage terabytes of information in databases.
Does Amazon use mainframes?
If Amazon’s AWS cloud unit has an Achilles Heel, it is that the company’s singular and enormously successful focus on the cloud has kept it from developing deep expertise with legacy mainframe systems that still run massive portions of the global economy.
Is Z OS still used?
z/OS remains IBM’s mainstay mainframe operating system today.
What do you need to know about a VTOC?
The VTOC lists the data sets that reside on its volume, along with information about the location and size of each data set, and other data set attributes. A standard z/OS utility program, ICKDSF, is used to create the label and VTOC.
Is it possible to extend the VTOC size?
The storage management team needs to offload all of the datasets and specify the VTOC size while reformatting the DASD. If you have ICKDSF Release 17 or later you can extend the VTOC without the need to offload any datasets.
How to expand VTOC in cylinder, head, N?
Moves and expands the VTOC into a new location. For cylinder,head,n, substitute the decimal or hexadecimal digits (for example, X’1A’,X’0′,X’3B’) to specify the beginning location and size of the new VTOC. The beginning and ending locations must not be the same as the old VTOC and a single extent free space must be available for the new VTOC.
What’s the highest address that can be referenced in VTOC?
The existing IBM software uses relative track addressing or the Track-Track-Record (TTR) format to process the VTOC. This restricts the highest address that can be referenced as a VTOC track to be 64K-1.