Services provided by CSRCESRV

Data compression and expansion services, which your program invokes through the CSRCESRV macro, are described as follows:

Data Compression Service
This service compresses a block of data that you identify and stores that data in compressed form in an output area. The service uses an algorithm called run length encoding, which is a compression technique that compresses repeating characters, such as blanks. In some cases, the service uses an interim work area.
Data Expansion Service
This service expands a block of data that you identify; the data must have been compressed by the data compression service. The data expansion service reverses the algorithm that the data compression service used, and stores the data in its original form in an output area. In some cases, the service uses an interim work area.
Query Service
This service queries the system to determine the following:
- Whether data compression is supported by the system currently installed
- The size of the work area required by the compression or expansion service.
To use the data compression and data expansion services, you need the information that the query service provides. Invoke the query service before invoking either the data compression or data expansion services.

Note: These services do not provide a recovery routine (for example, ESTAE or FRR) because it would not contribute to reliability or availability.