You are a store-through user who plans to use a data item but not update it. Serializing this process ensures that no one updates the data item while you hold the lock.

1. Obtain a shared lock by using the IXLLOCK macro. Holding a shared lock enables others to also use, but not update, the data item.
2. If there is a copy of the data item in your local cache buffer, use the IXLVECTR macro to determine if the copy is valid. If the copy is valid, go to step 5.
3. If a copy does not exist in the local cache buffer or the copy is no longer valid, use IXLCACHE REQUEST=READ_DATA to read the data item from the cache structure. If the data item is in the cache structure, go to step 5. If a local cache buffer is not assigned to the named data item, assign the local cache buffer and use a protocol to assign a vector entry to the buffer.
4. If the data item is not in the cache structure, read it from permanent storage into the local cache buffer.
5. Use the data item as needed.
6. If the data item has been read from permanent storage, use IXLCACHE REQUEST=WRITE_DATA to write it to the cache so the system can register your interest. Otherwise, skip this step and go directly to step 7.
7. Use the IXLLOCK macro to free the shared lock.