Help! Running Informix Online on SCO

We are struggling with getting Informix Online 7.2 to come up on SCO Open Server Enterprise 5.0.2. I know it can be done, I have received emails from many people stating that they are doing this successfully. And this platform is supported by Informix. Our consenus is that we just have not found the right settings for kernal parameters. We have methodically tried many settings on many parameters and Informix just won't come up. This is what we get in 'online.log' each time we do oninit: 16:43:02 shmat: [ENOMEM][12]: out of available data space, check systemMAXMEM 16:43:02 mt_shm_init: can't create resident segment This would seem to suggest that its not getting enough memory somehow. Any help would be greatly appreciated. We have worked extensivly with Informix tech support on this and they seem to be stumped too. The machine has 128 megs of RAM and will be dedicated to running one Informix application and nothing else.