Hi Sudhir,
I think that depending on you Ibm-Informix version, the size of the name the tables was incremented of 18 to 128 characters.
Please test running:
SELECT substr(a.tabname,1,22), b.colno,
substr(b.colname,1,22), b.coltype, b.collength
FROM systables a, syscolumns b
WHERE a.tabid = b.tabid
ORDER BY b.colno
Gustavo.