_EDC_ADD_ERRNO2

Controls whether or not errno2 is appended to the output of perror(), strerror(), and strerror_r(). The errno2 might be set by the z/OS XL C/C++ runtime library, z/OS UNIX callable services, or other callable services. The errno2 is intended for diagnostic display purposes only and it is not a programming interface.

The variable _EDC_ADD_ERRNO2 is not set by default. When the variable _EDC_ADD_ERRNO2 is not set, errno2 is added to perror() messages, but not to messages retrieved by using strerror() or strerror_r(). When _EDC_ADD_ERRNO2 is set to 1, errno2 is added to perror(), strerror(), and strerror_r() messages. For all other values of _EDC_ADD_ERRNO2, errno2 is not added. For example, for perror(), if errno was 121, the default behavior might produce the following message "EDC5121I Invalid argument. (errno2=0x0C0F8402)".

_EDC_ADD_ERRNO2 is set to zero with the command:

setenv("_EDC_ADD_ERRNO2","0",1);

It is suggested that applications run with _EDC_ADD_ERRNO2 not being set. This causes errno2 to be added only to perror() messages.

If an application is using strerror() or strerror_r() to retrieve messages associated with an error number, usually a saved errno value, it is suggested that errno2 also be saved by using __errno2() at the time when errno is saved. The application can then process the retrieved message and saved errno2 value as a pair.

Note: Not all functions set errno2 when errno is set. In the cases where errno2 is not set, the errno2 might be a residual value. You might use the __err2ad() function to clear errno2 to reduce the possibility of a residual value being returned.