DFHMAC-USERDATA is used by the service requester to
pass application data to the stub program DFHMADPL.
This is an optional container that can be sent by the service requester
along with the DFHMAC-REQUESTV1 or DFHMAC-ALLPARMS containers. When the adapter
service successfully processes the request message, any application data that
is required in the response is returned in this container.
The length of
the container can be up to, but not equal to, 16MB.