subprogram / mudule/ service pgm , which one?

[thelearner]

Hi,

Between these 3:
1.Subprogram (a pgm that is called by calling pgm but not bound with the calling pgm, just like in OPM.
2.Module(bind by copy)
3.service pgm( bind by reference)

In what kind of case I should use which one of the above?
What's the preference?

Thanks

 

[arrow483]

Bind by copy: Fastest because it binds at compile time (a copy of the module is in the pgm). Best for static procedures that are unlikely to change. Like date conversion, for example.

Service pgm: It binds at run time. Allows you to change the module, without having to find every pgm that referenced it.

Sub-Program: Better for seldom used modules, perhaps? Most important, runs in default ILE environment, and so can be used in shops that are using RPG-IV, but haven't implemented ILE.