Mainframe Interview Questions

No. The mode is specified via the SYSCTL DD card in the JCL.

The INTO option moves the information in the TIOA into the reserved specified area, while the SET option simply returns the address of the TIOA to the specified BLL cell or address of a linkage-section.

Because SALARY is not declared to have NULLs and the employees for whom the salary is not known are also counted.

The simplest DB2 index is the B-tree and the B-tree's top page is called the root page. The root page entries represent the upper range limits of the index and are referenced first in a search. 

PCT (Program Control Table) - Defines each transaction containing a list of valid transaction identifiers (transid) where each transaction is paired with its matching program.

PPT (Program Processing Table) - Contains a list of valid program names and maps and whether a current version is in the CICS region or needs to be brought in as a new copy.

FCT (File Control Table) - Contains a list of files known to CICS, the dataset name and status (closed/open, enable/disabled)

TCT (Terminal Control Table)- A list of the terminals known to CICS.

Primary key : a relational database constraint. Primary key consists of one or more columns that uniquely identify a row in the table. For a normalized relation, there is one designated primary key.

Unique index: a physical object that stores only unique values. There can be one or more unique indexes on a table.

Customer Information Control System (CICS) is an online transaction processing monitor from IBM that acts as an interface between the operating system and application programs to provide rapid high-volume online transaction processing.

DB2 use the multiple indexes to satisfy multiple predicates in a SELECT statement that are joined by an AND or OR.