getting errno and its text description

The return value I am getting from a call to open( ) is -1.  My non ibm
documentation of the C standard says that -1 indicates an error and to look
to the "errno" global variable for the error code.

Am I going too far if I write a CPP routine to retrieve the value of errno?
Is there an ile/rpg way to retrieve errno?

Also, is there a function that can be called that converts the errno to text
form?

thanks,

Steve