Thanks David,
Maybe I was too vague in the problem description.
Programs on HP-UX with ServerExpress 5.1 were based on MQCONN-calls with MQSERVER/MQCHLTAB/MQCHLLIB set (no authentication required).
On RHEL 6.6 with VC 2.2 we have to use MQCONNX-calls to supply UID/PW since new setup on the MQ-server is using CapitalWare's MQAUSX.
As IBM Websphere documention nowhere mentions support for VC (only ServerExpress/NetExpress), initial thought was that it wasn't supported. In meantime have received confirmation that it is supported.
Have it working now , be it that the solution might not be as it should be.
Changing MQCSP-CSPUSERIDLENGTH and MQCSP-CSPPASSWORDLENGTH from 'USAGE BINARY' to 'USAGE COMP-5' in the IBM-supplied CMQCSPV-copybook made it work.
The values itself are passed with pointers (set MQCSP-CSPUSERIDPTR to address of ws-uid.).
Dirk