The iconv utility reads characters from the input file, converts them from fromCodeSet encoding to toCodeSet encoding, and writes them to the output file.
The conversion is performed by the code conversion functions of the runtime library. They are described in Code conversion functions. The tables used are determined by the CC codes of the fromCodeSet and toCodeSet appended to the four-character prefix. The prefix is EDCU for non-XPLINK converters, CEHU for XPLINK converters, and CEQU for AMODE 64 converters. See z/OS XL C/C++ User's Guide for descriptions of the genxlt and iconv utilities. There is also a UNIX System Services iconv utility, which is described in z/OS UNIX System Services Command Reference.
The iconv utility can also perform bidirectional layout transformation (such as shaping and reordering) while converting from fromCodeSet to toCodeSet according to the value of an environment variable called _BIDION. The value of this variable is either set to TRUE to activate the BiDi layout transformation or FALSE to prevent the bidirectional layout transformation. If this variable is not defined in the environment it defaults to FALSE. The _BIDIATTR environment variable can be used to contain the bidirectional attributes (for information on bidirectional layout transformation see Bidirectional language support) which will determine the way the bidirectional transformation takes place. These two environment variables are described in Using environment variables.