Field-level sensitivity

Field-level sensitivity provides a number of benefits related to the data-independence of application programs, enhanced data security, and increased flexibility in the formatting of segment types.

Field-level sensitivity gives you an increased level of data independence by isolating application programs from:

In addition, field-level sensitivity enhances data security by limiting an application program to a subset of fields within a segment, and controlling replace operations at the field level.

Field-level sensitivity allows you to reformat a segment type. Reformatting a segment type can be done without changing the application program's view of the segment data, provided fields have not been removed or altered in length or data type. Fields can be added to or shifted within a segment in a manner transparent to the application program. Field-level sensitivity gives applications a segment organization that always conforms to what is specified in the SENFLD statements.

The following database types support field-level sensitivity:

Using field-level sensitivity as a mapping interface

Field-level sensitivity acts as a mapping interface by letting PSBGEN field locations differ from DBDGEN field locations. Mapping is invoked after the segment edit routine on input and before the segment edit routine on output. When creating a sequential data set from database information (or creating database information from a sequential data set), field-level sensitivity can reduce or eliminate the amount of formatting an application program must do.

Using field-level sensitivity with variable-length segments

If field-level sensitivity is used with variable-length segments, you can add new fields to a segment without reorganizing the database. FIELD definitions in a DBDGEN allow you to enlarge segment types without affecting any previous users of the segment. The DBDGEN FIELD statement lets you specify a field that does not yet exist in the physical segment but that will be dynamically created when the segment is retrieved.

Field-level sensitivity can help in the transition of an application program from a non-database environment to a database environment. Application programs that formerly accessed z/OS® files might be able to receive the same information in the same format if the database was designed with conversion in mind.

Field-level sensitivity is not supported for DEDBs and MSDBs.