Using the IXCSETUS Macro

Two ways to use the IXCSETUS macro are as follows:

An active member can issue IXCSETUS to change its own user state value.
An active member can issue IXCSETUS to change the user state value of another member in the same group. (The target member can be in any of these states: created, active, quiesced, or failed.)

When you issue the IXCSETUS macro, you provide the value (NEWUS parameter) that you want XCF to place in the user state field of the target member. Before making the change, you can take advantage of the compare and swap capability of the IXCSETUS macro to serialize the user state field.

If you code IXCSETUS and attempt to change a user state value without first doing a compare, XCF still checks the current value. If the current value equals the new value you specify on NEWUS, XCF does not make the change, does not notify the other members, and returns an unsuccessful completion code.