big problem when I use dbopen

hello, I encounter a big problem when I use freeTDS.
My program must receive thousands of connections from different users. When
I have open these handles, if I use "dbopen()"  of freeTDS,the problem will
core dump at once.

You can simply test the situation in this way:
first turn on the ulimit -n on Linux to append open files to a high num,
saying, 10240;
and then open more then 1900 handles of one file and do not close them,and
then try to "dbopen()", the problem will immediately core dump.

FILE *fp[2000]
for(int i=0;i<1900;i++)
(
    fp[i]=fopen("noclosefile","r");
    //don't close them;
)
.....

dbopen();

then the problem will core dump!
thanks for you help!