umask is not an environment variable. It is a utility. Try this.
However this umask will create a permission string of 002 which I doubt that you want. The mask is the binary opposite, or complement, of the permission string that you want. If you want a permission string of 775 then the umask value is 002.
Also the executable bit is never set when a file is created. You always have to set the executable bit manually after the file is created.