To ensure that your CICS® TG connects to the expected CICS server, you can specify CICSAPPLID and CICSAPPLIDQUALIFIER in the IPICSERVER definition in the ctg.ini file.
SECTION IPICSERVER = A1-IPIC
SRVIDLETIMEOUT=0
HOSTNAME=cicssrv2.company.com
PORT=50889
CONNECTTIMEOUT=60
TCPKEEPALIVE=Y
SENDSESSIONS=100
CICSAPPLID=IY2GTGXX
CICSAPPLIDQUALIFIER=GBIBMIYA
ENDSECTION
DFHIS1013 ... Invalid applid GBIBMIYA.IY2GTGXX received in capability exchange
request on TCPIPSERVICE SRV50889.