Transparency User Exit

The Transparency User Exit enables you to gain control during compression and expansion in order to avoid or recover from errors. You can receive control from CA Compress for each record before and after compression and before and after expansion. Through the CA Compress/2 parameter list, described in the chapter CA Compress/2, you have access to the record in both its compressed and uncompressed state, as well as to its length and other information. By setting the return code at PRECMP and PREXPD, you can prevent compression and expansion where appropriate. After taking corrective action, you can recover at POSTCMP and POSTXPD from compression and expansion errors resulting in I/O errors and messages such as SHR014I, SHR015I, and SHR010I.

The exit is powerful, and you should have a good understanding of the material in the chapter CA Compress/2, and of the parameters you receive in the exit before you manipulate them in any way. Errors in the user exit may lead to I/O errors or even data loss, so always test any changes carefully before enabling the exit for any production data set. You receive addressability to the ddname, the data set name, and the TCB, which gives you ready access to the jobname, so you can use these values to control your processing. You can use RACF or an equivalent product to control access to the module name, ZUXITMOD.