Before you use your copy of a data item, you must test the local cache vector entry assigned to that data item to determine if the copy is current. IXLVECTR REQUEST=TESTLOCALCACHE enables you to test the vector entry for the validity of a data item in your local buffer.

In Figure 1, connecting user B checks vector entry 4 to test the validity of data item Z. In the example, the vector entry indicates that the data is not valid. If a data item in your local cache buffer is not valid, IXLVECTR returns an appropriate response. To refresh data item Z in the local buffer, connection B must read the data item from the cache structure and again register interest in data item Z.

The IXLVECTR macro also allows you to test for connectivity failure between your system and the coupling facility through the VALIDATE=YES option. If connectivity to the coupling facility is interrupted, specifying VALIDATE=YES on IXLVECTR allows the system to invalidate the local cached copy of the data item. This helps ensure data integrity because cross-invalidate might not have occurred during the temporary loss of connectivity.