Mainframe Interview Questions

Go to file-aid copy option.Enter the from dataset to be copied and to dataset to which you want to copy.go to options. Enter 0 at Initial records to skip field.Then enter 3 at the no of records to skip field and 1 to no of records to select.press enter and PF3.

The number of distinct values for a column is called index cardinality. DB2's RUNSTATS utility analyzes column value redundancy to determine whether to use a tablespace or index scan to search for data.

- A status occurs when image copy on a table needs to be taken

- The table is available only for queries and can not be updated

- COPY PENDING status can be removed by taking away the image copy or by using REPAIR utility

A31. The self-referencing constraint limits in a single table the changes to a primary key that the related foreign key defines. The foreign key in a self referencing table must specify the DELETE CASCADE rule.

USING HOST VARIABLE we can pass data from COBOL to DB2

COMMIT statements are used to release locks which are required for that unit of work, and then permit a new unit of work. In other words, if COMMITS are not coded in the program and the program has been sent for execution, then while processing, in place of just going back to a few inserts since the nearest commit, the program has to go back to the inserts which were made during the entire run of the program. This extra process takes around twice or thrice the time taken normally.

Following guidelines to be following while writing Cobol program:

- Use ? EVALUATE ? statement for constructing cases.

- Use scope terminators for nesting.

- Use in-line Perform statement for writing ?do? constructions.

- Use Test Before and Test After in the Perform statement while writing Do-While statements.

The LOAD command retrieves an object program from disk and loads it into main storage - it's primarily used for a constant table that will be available system-wide.