Location Mode in IDMS:

The assignment of record to a particular page in the area is determined by the location mode.

There are types of location modes : CALC, VIA and DIRECT.

CALC:

In CALC mode records are stored on or near a page calculated by IDMS. CALC mode uses the Hashing algorithm to access the records. Hashing Algorithm in CALC mode converts the field value in the record as a combination of page number and line number. Records can be accessed directly with the field value.

VIA:

Records are clustered on the same physical page as the owner. In VIA mode records are placed near the Owner. VIA mode allows efficient navigation as the records are clustered and are close to the owner.

DIRECT:
Records can be stored in application developer specified location. Records are stored on the page as close as possible to the specified location.