During initialization, JES automatically attaches to XCF to establish itself as a member of the JES XCF group. If you plan to use the JES XCF macros and exits, IBM recommends you first try to use the JES attachment instead of creating your own attachment. To do so, use exit IXZXIT01 to get control when JES or your installation sends message data; use IXZXIT02 to get control when JES or your installation receives message data, and code IXZXIT03 only to obtain a storage area to be shared by exits IXZXIT01 and IXZXIT02.