Mainframe: Virtual Storage Access Method [VSAM]

This course consist of:

1. What is VSAM?

2. Cluster Definition

3. Differences between VSAM and NON-VSAM datasets

4. Differences between KSDS, ESDS, RRDS and LDS

5. What is Control Interval (CI) and Control Area (CA)

6. How to create KSDS, ESDS, RRDS files using IDCAMS utility 

7. Explained different IDCAMS utility commands

8. DEFINE

9. REPRO

10. PRINT

11. DELETE

12. LISTCAT

13. ALTER

14. File Manager tool

15. DITTO tool

This course is totally practical oriented hence you will get almost all concepts explanation on Mainframe Shop.

What is VSAM?

The term Virtual Storage Access Method (VSAM) applies to both a data set type and the access method used to manage various user data types.

As an access method, VSAM provides much more complex functions than other disk access methods. VSAM keeps disk records in a unique format that is not understandable by other access methods.

Different type of VSAM datasets:

Key Sequence Data Set (KSDS)

This type is the most common use for VSAM. Each record has one or more key fields and a record can be retrieved (or inserted) by key value. This provides random access to data. Records are of variable length. IMS uses KDSDs.

Entry Sequence Data Set (ESDS)

This form of VSAM keeps records in sequential order. Records can be accessed sequentially. It is used by IMS, DB2, and z/OS UNIX.

Relative Record Data Set (RRDS)

This VSAM format allows retrieval of records by number; record 1, record 2, and so forth. This provides random access and assumes the application program has a way to derive the desired record numbers.

Linear Data Set (LDS)

This type is, in effect, a byte-stream data set and is the only form of a byte-stream data set in traditional z/OS files (as opposed to z/OS UNIX files). DB2 and a number of z/OS system functions use this format heavily, but it is rarely used by application programs.