Accessing and Managing Data Within a Cache System

When you initially allocate a cache structure using the IXLCONN macro, the structure contains no user-defined data. If you plan to use a store-in or store-through cache method, you store the data in the cache structure. First, you read the data from permanent storage to your local cache buffers. Next, you use the IXLCACHE macro to write the data from the local cache buffers to the cache structure. (See Table 1 for a summary of IXLCACHE request types and services to use with the cache structure.)

Providing the Connect Token (CONTOKEN)
Each user must issue any IXLCACHE request in the connector's address space, that is, from the address space where the IXLCONN macro for the connection is issued. To identify the connection, your IXLCACHE request MUST include the CONTOKEN keyword. (CONTOKEN must contain the connect token that the system returns to the answer area of IXLCONN when the user issues the IXLCONN macro to establish the connection to the cache structure. The system returns the connect token in the CONACONTOKEN field of the answer area for IXLCONN.)
Providing a Request Identifier (REQID)
To identify your request, you can optionally use the REQID keyword. Coding REQID is useful for recovery routines, or for developing protocols to use with a resource manager that needs to purge coupling facility requests from the system through the use of the IXLPURGE macro. One way to use IXLPURGE is to purge only those requests for a specified connect token (that is, requests associated with a specified connector to the cache.) Specifying the REQID keyword on an IXLCACHE request provides a means for the resource manager to further limit or filter the set of requests that it purges to include only requests for both the specified connect token and the REQID. Users of each connection are responsible for establishing protocols for the use of the REQID keyword and the IXLPURGE macro.