Keyed interface

Keys are API-specific values that inform an API that a certain function should be performed. Keys are also used to pass information to an API or to retrieve information from an API.

Through the use of keys, you can be more selective; you can choose one item or a number of items rather than all of them. For example, using the List Job (QUSLJOB) API, you can receive selected information about a job based on the keys that you specify. If you want job information about the output queue priority, you only need to specify the output queue priority key.

Although there are some exceptions, the keys are typically supplied and passed to an API through a variable-length record. A variable-length record is a collection of information that specifies the key being used and the data that is associated with the key. If a given structure contains binary values, it must be 4-byte aligned.

Some APIs that use variable-length records in addition to the QUSLJOB API are the Change Object Description (QLICOBJD) API and the Register Exit Point (QUSRGPT, QusRegisterExitPoint) API. You can use the appropriate include file in member QUS in the system include (QSYSINC) library when you have variable-length records as either input or output.

A keyed interface provides an easy-to-use means for enhancing an API without affecting the user who chooses not to use the enhancements.