z/VSE 5.1: Did you know, that z/VSE supports 64 bit I/O ?
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z/VSE introduced 64 bit virtual addressing with z/VSE 5.1 in November 2011.
An application may request 64 bit storage by creating or sharing a memory object (chunk
of virtual storage). The IARV64 services manage storage above 2 GB (above the bar).
Since December 2012 you may allocate (64 bit) I/O buffers above the bar. I/O operations
are supported on private memory objects only. Private memory objects can be accessed
by the application (partition) that created it.
64 bit I/O is supported via the EXCP (Execute Channel Program) service and for DASD (ECKD).
A new parameter was added to the CCB (Command Control Block) macro: IDAW=FORMAT2.
The CCW (Channel Command Word) with the IDA (Indirect Data Address) flag and
data address points to the Format 2 IDAW (Indirect Data Address Word).
The Format 2 IDAW contains the 64 bit address, the address of the I/O buffer.
The 64 bit I/O suuport is available with APAR DY47