Creating Dataviews for VSAM Files › Runtime Considerations for VSAM Dataviews › Validating the Dataview at Runtime

Validating the Dataview at Runtime

The first time a VSAM dataview is accessed during the execution of a program, the dataview is validated for the following attributes:

• File organization (ESDS, KSDS, or RRDS)
• Maximum record length (determined by totaling the lengths of the fields defined in the Field Definition fill‑in)
• Displacement and length of each primary and alternate key defined in the Dataview Key Definition fill‑in

The source against which the attributes of a VSAM file are validated depends on the runtime environment. In CICS, the FCT entry for the base cluster and alternate path are used. The FCT entry for variable‑occurrence or variable‑segment files must indicate that the file has records of varying lengths. In all other environments, the information is obtained by opening the relevant data sets.

The extent of validation depends on the update attribute of the dataview. If the dataview is updateable in the current program, the whole upgrade set defined for the dataview is validated (for KSDS data sets). If the dataview can only be read (as defined in the program, in the dataview definition, or at runtime), only the current access path is validated. Index uniqueness and membership in the upgrade set are not validated.

If validation fails, a runtime error results.