Create a direct data set with the basic sequential access method (BSAM). Use the MACRF=WL parameter in the BSAM DCB macro to create a direct data set.

The application program must synchronize all I/O operations with a CHECK or a WAIT macro.

The application program must block and unblock its own input and output records. (BDAM only reads and writes data blocks.)

You can find data blocks within a data set with one of the following addressing techniques.

Actual device addresses. This specifies the actual location.

Relative track address technique. This locates a track on a direct access storage device starting at the beginning of the data set.

Relative block address technique. This locates a fixed-length data block starting from the beginning of the data set.

BDAM macros can be issued in 24-bit or 31-bit addressing mode.