The Circular Access Method is used to write, and read back, a circular log of records into a file that never exceeds a given amount of space.
The Circular Access Method can read or write text or binary data, but is mostly used to write application logs on systems where disk space is limited and critical. Writing to a circular log means that the log file size is allocated at start time and will never change. This protects against an application that repeatedly emits information about an error condition that occurs over and over and would normally fill up the available disk space as the log grows. The circular log, once physically full, wraps around to the start and begins overwriting the oldest records in the log. On being read the log holsd the information to allow the reader to start at the beginning of the logical file and to read all available records from that point on.