Appendix F of the z/OS® Support for Unicode: Using Conversion Services manual, SA22 -7649, records those conversions which are supported though these services. CICS® now supports any of these character conversions by making use of the z/OS conversion services.
The conversions entries that you select must not specify type ER.
The z/OS conversion services support big endian byte ordered data (UTF-16BE),
they do not support little endian byte ordered data (UTF-16LE). When
asked to convert UTF-16LE source data to some other CCSID, CICS transforms
the data to the big-endian form of UTF-16 before calling the z/OS conversion
services. When the target data is identified as UTF-16 (CCSID 1200), CICS receives the
converted data from the z/OS services in big-endian byte order, and returns it
in this form.
There are 3 CCSIds for UTF data,
When handling CCSID 1200, CICS respects the byte order marker for inbound conversions, but is not able to retain that information when handling a related outbound conversion. All outbound data for CCSID 1200 is UTF16-LE. Application programmers need to know about this and perform their own LE to BE conversions if they so require.