Mainframe Interview Questions

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.

While allocating KSDS Datasets, free space is declared at regular intervals at the time of initial loading. This is done because this free space is utilized for keeping the data arranged in sequence physically, even though inserted randomly.

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.

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.

GROUP BY partitions the selected rows on the distinct values of the column on which you group by. HAVING selects GROUPs which match the criteria specified

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. 

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

They are DEFINE CLUSTER, DATA and INDEX.