4GL runtime error -4339 (4GL has run out of data space memory)

I am getting a 4GL run-time error -4339 "4GL has run out of data space memory" This occurs in a fairly complex report with some extensive sorting and grouping criteria, and processing in the order of 45,000 records. Informix Tech Support suggested increasing the amount of memory available to each process. I increased the MAXUMEM kernel parameter to 8192 which is SCO's max. Having done this I was able to process about 40,000 records (about 20,000 more than before) but it still crashed before all records were processed I'm running Informix-4GL v4.12.UE1 and Informix-SE 5.02.UC6 on SCO Unix v3.2.4.1. What's really strange is that the exact same report ran fine on Informix 4GL v4.00 and Informix-SE v4.00. Any help would be greatly appreciated. =Dan=