Execute Direct Access Program: Difference between revisions

Revision as of 18:00, 19 October 2011

Revision as of 18:13, 19 October 2011

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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/360 System Programmer's Guide<ref>http://www.bitsavers.org/pdf/ibm/360/os/R01-08/C28-6550-2_OSsysPrmg_Mar67.pdf</ref>.

Existing blocks may be read or updated. The dataset may not be created nor extended using XDAP; for that purpose a true access method is required. XDAP may coexist with BSAM or BPAM, and several OS components are implemented in this way.