The segment exit allows a user-written program to control segment selection and modify segment data during load and unload processing. The exit program is called for each database segment. It can delete the segment, modify the segment data or pass it through unchanged. If a segment is deleted, all of its children segments are automatically deleted. The segment exit is enabled using the SEGEXIT directive.
The compression exit is used for the input file to the Load and the output file for Unload. It allows for segment compression and/or encryption of the input or output files. It is not used for the data stored in the MFIMS database. A standard routine named CBLDCIMS is provided to decompress input and compress output files. A user-written program can perform different segment encoding. This exit is enabled using the COMPRESS directive.
The IMSDBUV sample program for unloading IMS/ESA databases can create compressed files for input to the IMSDBU Load and decompressed using the CBLDCIMS routine.
Details of these exits are documented in the sample file DBUPARMS.CPY.