Load data with a extent Problem!

Hi, We have a ids 9.40 FC3 on a SUN BOX we are trying to upload data in three tables. Our database needs to be BUFFERED. Firstly, we upload a flat table to proccess its data with a SP. We have a integer primary key in three tables and we run that SP in two sessions to procecess data from flat table an insert them into three tables that I mentioned above( that's because we need to run this proccess quickly). We pass a parameter to define which integer range of values are going to be assigned like PK to each tabla in each SP session, that's is to avoid unique problem. Three production tables has lock row mode. Once you know our enviroment, when we run that SP in two session and three table get a extent size of 16k and next extent size of 16k, process runs well, but when three table has a calculated big initial extent size, Informix send us a dead lock once ' three times. Does anyone know what it could be? What are we doing wrong? Thankx