Re: User Space question

On 04-Dec-2014 15:05 -0600, Monnier, Gary wrote:

Look at QUSCHGUS's parameter 5 - Force changes to auxiliary storage

Force changes to auxiliary storage INPUT; CHAR(1) The method of
forcing changes made to the user space to auxiliary storage. The
valid values are as follows:

0 Does not force changes. Normal system management writes the
changes to auxiliary storage.

1 Forces changes asynchronously. This interrupts the normal system
management and ensures that the user space is written to auxiliary
storage.

2 Forces changes synchronously. This interrupts the normal system
management and ensures that the user space is written immediately to
auxiliary storage.

Or use a pointer to the space (QUSPTRUS api). Obtaining a pointer
to the user space will provide virtually immediate update when the
value for the space is changed.

Updates to the data via a pointer is the equivalent of choosing zero as the value for that "force" option of [when using] the Change User Space API. The immediacy of the changes to the data is the same irrespective of the updates being made via pointer or via that API; whether those changes [as made by either means] remain visible on DASD or instead may be lost per having been made only in memory, depends on whether and when the changes are being /forced/ to disk.

The Set Access State (SETACST) [or less desirable Ensure Object (ENSOBJ)] MI instructions allow asking the Storage Management to [a]synchronously /force/ the [changed] data [and object]. With such a request, the system Storage Management is prodded rather than acting /normal/; in contrast, the _normal system [storage] management_ would choose to force the data\object on its own accord via some algorithm that decides upon the scheduling of that action.