Using CA Tape Encryption in Your z/OS Environment › Integrated Compression for Symmetric Key Encryption › How You Manage the Compression Process

How You Manage the Compression Process

You manage the compression process by defining the two compression attributes, Compression= and MinimumCompressionRate=. These options can be specified in the dynamic options and symmetric key options of parmlib to control how compression operates. After you set up these options, the compression process runs transparently. The following points outline the compression process:

Note: For detailed information about these attributes and the available compression methods, see the Configuration Guide.

• The compression attributes in the dynamic member of parmlib specify global settings for managing compression.
  • The Compression= attribute determines the following actions:
    • If compression will be performed.
    • If compression will be performed for all tapes that are to be encrypted.
    • If compression will be determined by the individual key definition.
  • The MinimumCompressionRate= attribute establishes a default value for the minimum compression rate.

  Note: The Compression= attribute specified in the dynamic options is applied globally and overrides any Compression= attribute in the symmetric key options. You can think of this global option logically as a master switch used to turn compression on or off for a given BES task.

• The compression attributes in the key definitions of the symmetric key options manage compression for specific symmetric keys. The files that are encrypted by the specific symmetric key are compressed, so you only compress the files that you want to compress.

  Note: The MinimumCompressionRate= attribute specified in the symmetric key options for a specific key overrides that setting in the dynamic options.

• The required compression and expansion programs and tables are automatically loaded and made resident when the first BES address space is started. This ensures that all the compression and expansion methods are always available so that they can be called when needed. No JCL changes or end-user application program changes are required.
• All the systems that might create the compressed and encrypted tapes and all systems that might read these tapes must be upgraded to a level of CA Tape Encryption that supports the integrated compression feature before you enable compression on those systems.
• The compression attributes in the dynamic options or symmetric key options can be changed at any time and you can refresh them with the REFRESH command.
• The compression attributes are checked by CA Tape Encryption before a file is encrypted.
• A compression identifier is included in the standard user labels on the tape when the tape is written.
• The compression identifier is used to determine how to expand the file when the tape is read.