what's the matter with error -25588

In my programs wrote in ESQLC, error -25588 encountered. My program forks several child processes,db connection is established in every process and keep alive till end of process. When I fork more processes, certain process will fail to establish connection to informix server(IDS 7.31). Since my program deployed on the same computer with IDS, we use onipcshm as commumication protocol.If I change onipcshm to onsoctcp,no 25588 error occur. What's the reason? Help me,pls. -- Message posted via http://www.dbmonster.com