security – set default file permission to read, write and execute in linux

I need to set default file permission on file creation to be 777 ie read , write and execute for everyone . However , umask for file uses 666 code i.e if I need permission to 444 , I could have write 666-222=444 (or umask 222 ) . But , in problem I need to set it to 777 .
So how can I achieve it ?