Previous topic |
Next topic |
Contents |
Contact z/OS |
Library |
PDF
Understanding the Object Access Method z/OS DFSMS OAM Application Programmer's Reference SC23-6865-00 |
|
The Object Access Method (OAM) is a component of DFSMSdfp, the base for the z/OS product. OAM uses the concepts of system-managed storage, introduced by z/OS, which provide functions for data and space management. z/OS offers the following advantages to its users:
OAM supports a class of data referred to as objects.
An object is a named stream of bytes. The content, format,
and structure of that byte stream are unknown to OAM. For example,
an object can be a compressed scanned image or coded data. Objects
are different from data sets handled by existing access methods. The
characteristics that distinguish them from traditional data sets include:
z/OS includes the definition of a storage hierarchy for objects and the parameters for managing those objects. OAM uses the z/OS-supplied hierarchy definition and management parameters to place user-accessible objects anywhere in the storage hierarchy. The location of an object in the hierarchy is unknown to the user. Device-dependent information is not required of the user; for example, there are no JCL DD statements and no considerations for device geometry, such as track size. OAM provides an application programming interface known as the object storage request (OSREQ) macro to store, retrieve, delete, query, and change information about an object. OAM includes the functions necessary to manage the objects after storing them. OAM stores objects in collections. A collection is a group
of objects that typically have similar performance characteristics:
A collection is used to catalog a large number of objects, which, if cataloged separately, require an extremely large catalog. Every object must be assigned to a collection. Object names within a collection must be unique; however, the same object name can be used in multiple collections. A collection can belong to only one storage group; however, a storage group can have many collections associated with it. |
Copyright IBM Corporation 1990, 2014
|