Although I increased the value of STACK_MAIN because 'low on stack!' message happens, the stack size is not changed when I see it by the 'top' command.
And also I changed all the stack values such as CONFIG_USERMAIN_STACKSIZE in deconfig file, but the stack size of a user made application module does not change.
Finally, the stack size changed after I increased the size in px4_task_spawn_cmd().
So my problem was resolved.