Online Memory-Limit ??

Hi, I got the following problem : I'm using Informix Online (7.12 UC1) on SCO Unix (3.2.4.2), my programs access the database on Windows-Clients using ODBC (ntersolv and Informix-CLI). The system is running since about 2 Years. Since a couple of days the engine terminates itself a few times a day showing these symptoms : Online.log : dynamically allocated new shared memory segment (size 8388608) (overall 5 times, sometimes in a few minutes, sometimes in a few hours) Then : shmat : [ENOMEM][12]:out of available dataspce, check system MAXMEM mt.c, line 5623,thread 50, proc id 663, invalid mutex Type, PANIC : Attempting to bring system down Onconfig : SHMBASE 0x0SHMVRTSIZE 12000 SHMADD 8192 SHMTOTAL 0 onstat -g ses, onstat -g seg : Engine is using 15 MB after startup, 55 MB just before shutting down. Physical memory was 80 MB, now I upgraded to 114 MB, but this seems to have no effect at all ! Btw. : I did not find the parameter MAXMEM at all, neither in Onconfig, nor as a kernel-parameter (like it is said in the release-notes !) What is restricting the use of memory to 55 MB on this system ? Thanks and bye..