1)"plugins:orb:max_unbounded_string_size" should be a positive integer.
When set zero or negative value to this, "org.omg.CORBA.BAD_PARAM: cannot unmarshal IOR encapsulation" exception wil be thrown when pass unbounded string between client and server.

When set a number with a fractional part to this, no value will be set to the variable.

2)Manual problem

The default value of this is "16" according to page 66 of "Orbix 6.3.7 Configuration Reference", however, itconfigure set "128" to this in newly created *domain*.cfg file by default.