I tried to run GAMS on my RS/6000 running AIX, but it was complaining that it could not find /bin/csh.
Parts of the GAMS system are shell scripts written in c-shell. These parts need to be executed by the c-shell which is invoked by /bin/csh. The c-shell on AIX is an optional program product, and is not loaded to the hard disk if you do a minimal installation. To install the c-shell afterwards, become super- user, put the original AIX distribution tape in the tape drive, and run smit instupdt. Follow the directions and answer the questions in the SMIT menus. Choose the package: bosext1.csh.obj. For more information consult the installation guide of AIX.