Mainframe / VSAM Interview Questions

Mainframe Interview Questions

Cobol | DB2 | JCL | JCL2 | VSAM | VSAM2

What is the COBOL RECORD KEY clause?

The RECORD KEY in the SELECT clause identifies the files primary key as it will be known to the program.

What is the purpose of the FILE STATUS clause in the SELECT statement?

The FILE STATUS field identifies the field that VSAM uses to provide information about each I/O operation for the file.

If you wish to use the REWRITE command haw must the VSAM file be opened?

It must be opened as I/O.

Explain the meaning and syntax for the START command.

The START command is used read other than the next VSAM record. A value must be moved into the RECORD KEY. The KEY clause is optional, but it can be used to specify a relational (equal, less than, etc.) operator.

What is the meaning of dynamic processing?

It's rarely used. It means one program uses both sequential and random processing for a VSAM KSDS file.

Name some common VSAM error conditions and codes.

They are end of file (10), duplicate key (22), record not found (23), VSAM logic error (90), open problem (92) and space problem (93).

What is the VSAM-code field?

It is a COBOL II enhancement to VSAM batch processing expanding the FILE STATUS field. It is defined in WORKING STORAGE as a six byte group item with three two byte elements, the normal return code, the function code and the feedback code.

What is a VSAM slot?

A relative record dataset (RRDS) consists of a specified number of areas called slots. Each slot is identified by a relative record number (RRN) which indicates its relative position in the file.

What is the utility program closely associated with VSAM?

IDCAMS, the access method services utility.

There are at least seven IDCAMS commands; name and explain each of them.

ALTER modifies information for a catalog, alternate index, cluster or path. BLDINDEX builds the alternate index, of course. DEFINE is used for ALTERNATEINDEX, CLUSTER or PATH. DELETE removes the catalog entry for a catalog, cluster, alternate index or path. LISTCAT lists information about the dataset. PRINT prints the dataset contents. REPRO copies records from one file to another.

What are the three levels of definition for the VSAM DEFINE?

They are DEFINE CLUSTER, DATA and INDEX.

What is the significance of the SHAREOPTIONS parameter?

It specifies how the file may be shared between jobs and between batch and CICS environments.

What is the meaning of the DEFINE MODEL parameter?

It specifies whether Daniela Pestova or Yamila - oops! Wrong models! The MODEL parameter allows you to model your cluster by modeling it after an existing cluster.

Mainframe / VSAM Interview Questions