message.log: lock table overflow

In informix message.log file, I found the following messages : 20:21:42 lock table overflow - userid ..., sessionid ... ... ( Similar lock table overflow messages omitted ) 20:28:40 lock table overflow - userid ..., sessionid ... By running 'onstat -g sql', I found 4 sessions with SQL ERR and ISAM ERR as follows SQL ISAM SQL ERR ERR stmt -240 -134 DELETE -211 -134 ... -211 -134 CREATE INDEX -243 -134 UPDATE -134 ISAM error: no more locks. -211 Cannot read system catalog catalog-table. -240 Could not delete a row. -243 Could not position within a table table-name. LOCKS of $INFORMIXDIR/etc/$ONCONFIG is set to 350000 Does the 'lock table overflow' message mean the server need more LOCKS? Can I solve the problem by increasing LOCKS value ? Any response to solve the problem is appreciated ! -- Fu-Xiong Lin