EXCP 64-bit Storage Considerations

For EXCP virtual requests, the system page fixes the I/O buffers associated with your channel program. These I/O buffers may reside in 31-bit or 64-bit virtual storage.

If the I/O buffers reside in 64-bit virtual storage (referred to as a memory object), you must follow the requirements below:

You must specify the CONTROL=AUTH parameter on the IARV64 macro request that creates the memory object. If you specify or default to CONTROL=UNAUTH on the IARV64 macro, EXCP fails when it attempts to page fix the storage.
The I/O buffers must not reside within a memory object backed by 1 MB fixed real page frames. For example, you cannot specify PAGEFRAMESIZE=1MEG or PAGEFRAMESIZE=MAX on the IARV64 GETSTOR request that creates the memory object. If you do, EXCP fails when it attempts to page fix the storage.