VSAM
Catalogs
VSAM maintains extensive information about data sets and the DASD space they occupy. It is kept along with a wide range of other information in a central location called the VSAM catalog.
A D V E R T I S E M E N T
Master Catalog
VSAM maintains extensive information about data sets and the DASD space they occupy. It is kept along with a wide range of other information in a central location called the VSAM catalog.
The VSAM catalog resides on a direct-access device. Some of the data set and data space related information it typically contains is indicated below.
- Location of DASD space reserved for the exclusive use of VSAM
- Amount of space allocated to different VSAM data sets
- Addresses of VSAM data sets
- Attributes of VSAM data sets
- Statistical information about VSAM data sets
The VSAM catalog is very important because a VSAM data set cannot exist until it is first defined in the catalog. This means that information about the data set is recorded in the catalog in the form of entries. Also, a VSAM data set cannot be accessed unless information about it can be obtained from the catalog. Therefore, the catalog must be available for use.
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