Introducing the Object Access Method

This section provides a brief introduction to Object Access Method (OAM). For more information, see the z/OS DFSMS Object Access Method Application Programmer's Reference.

In OAM, an object is a stream of bytes with a name. The content, format, and structure of that byte stream are unknown to OAM. For example, an object could be a compressed scanned image, or coded data. There are no individual records within an object.

A collection is a group of objects that typically have similar performance, availability, backup, retention, and class transition characteristics. Every object must be assigned to a collection. Object names must be unique within a collection; the same object name can be used in different collections.

OAM is an access method of MVS∕DFP, the base for DFSMS. OAM uses the SMS-supplied hierarchy definition and management parameters to place user-accessible objects anywhere in the storage hierarchy. The hierarchy consists of DASD, library-resident optical volumes, and shelf-resident optical volumes. The location of an object in the hierarchy is unknown to the user; device-dependent information (such as track size) is not required.

The storage class and management class may be overridden by your installation defaults.