Execute Direct Access Program: Difference between revisions

Revision as of 05:10, 28 November 2012

Revision as of 08:06, 10 January 2013

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{{Mainframe I/O access methods}}

In [[IBM mainframe]] [[operating system]]s, '''Execute Direct Access Program''' ('''XDAP''') is a pseudo access method for accessing direct access datasets on a block by block basis. XDAP is more specifically described in the OS System Programmer's Guide.<ref>http://www.bitsavers.org/pdf/ibm/360/os/R01-08/C28-6550-2_OSsysPrmg_Mar67.pdf</ref>.

==Existing Blocks==

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==List and Execute Forms==

List and Execute forms of XDAP are supported, whereby a prototype form, called the List Form, is expanded as data, and a functional form, called the Execute Form, is expanded as instructions. XDAP is also supported conventionally, in which case the two forms are combined and is expanded as inline data and instructions. The use of List and Execute Forms facilitates the development of re-enterable programs.

==XDAP implicitly invokes EXCP==