The Object Access Method (OAM) help to access files in the operating system (OS) via certain command line codes. Unlike other access methods that are made for generic systems, the object access method is only fitted to work with the z/OS®. OAM is made specifically to help with storing files, and it normally can hold up to 2 gigabytes (GB) of data. OAM has been around for more than two decades, yet has received little recognition for its important role in data storage. It was developed in the late ’80s as a prototype product for an insurance company to replace microfiche and has since evolved into one of the most widely used data-archiving solutions on System z* servers. OAM is part of DFSMSdfp, a base element of z/OS*, and is typically used for storing archive-type data. OAM stores your object data and also manages the lifecycle of your object data from creation to expiration within a storage hierarchy consisting of multiple levels—disk, optical and tape.
Files traditionally are in digital catalogs, but the entire file set itself is cataloged with OAM. Another difference between OAM and other access methods is that all files are recorded as a stream. An “object,” which is also called unstructured data, is a named stream of bytes that has no record orientation. As stated earlier, OAM views an object as a data stream and no matter what the object contains—company emails, billing statements, medical images—OAM can store any object up to 2000 MB.