Performing OS I/O operations

This topic describes using OS I/O, which includes support for the following:
Notes:
  1. z/OS® XL C/C++ does not support BDAM, ISAM, or non-VSAM keyed data sets. Attempting to open a non-VSAM keyed data set for read or append fails; attempting to open an existing non-VSAM keyed data set for write results in unpredictable results.
  2. z/OS XL C/C++ provides complete read and write support for large format sequential data sets when seek is requested (not specifying the noseek keyword) and when noseek is requested and honored.
  3. z/OS XL C/C++ provides support for extended format sequential data sets in the extended addressing space on extended address volumes (EAVs).
  4. z/OS XL C/C++ supports opening DDNAMEs that have been dynamically allocated with the XTIOT, UCB nocapture, and DSAB-above-the-line options specified in the SVC99 parameters (S99TIOEX, S99ACUCB, S99DSABA flags).

OS I/O supports text, binary, record I/O, and blocked I/O, in record formats: fixed (F), variable (V), and undefined (U). For information about using wide-character I/O with z/OS XL C/C++, see z/OS XL C Support for the double-byte character set.

This topic describes C I/O stream functions as they can be used within C++ programs. If you want to use the C++ I/O stream classes instead, see Using the Standard C++ Library I/O Stream Classes for general information. For more detailed information, see Standard C++ Library Reference, which discusses the Standard C++ I/O stream classes