Hi Ajay,
you might want to check out the LastPlanText connection property. It is a SQL Anywhere function, so I don't know if it returns anything helpful on IQ. If it does, I think it's the closest thing to sp_showplan you can get.
This requires a special server option -zp to be set. According to manuals, it can be set for a running server using the sa_server_option system procedure but I was not always successful with it. It can be accompanied by the LastStatement connection property which requires the -zl server option.
For an overview, you can select and filter on the sa_conn_properties result set
> select * from sa_conn_properties () [where ...]
HTH
Volker