Re: Passing Parameter as Variable vs as address of variable

Yes the answer is the same for both - parameters are by default passed as pointers. For programs that is the only option.

BUT for procedures the mechanism for passing those pointers is different. They are passed on the stack and not via a special system mechanism. This allows for an additional option - passing by value rather than the address. By adding the VALUE keyword to a procedure parameter's definition you cause the actual value of the variable to be copied onto the stack and not a pointer to its storage.

If you want to dig into the details try these articles: https://www.itjungle.com/2016/11/29/fhg112916-story01/ <https://www.itjungle.com/2016/11/29/fhg112916-story01/> and https://www.itjungle.com/2017/02/20/guru-parameter-passing-fundamentals-programs-versus-procedures/ <https://www.itjungle.com/2017/02/20/guru-parameter-passing-fundamentals-programs-versus-procedures/> - the second one directly addresses your question.


Jon P.

On Aug 25, 2023, at 10:23 AM, Vinay Gavankar <vinaygav@xxxxxxxxx> wrote:

Hi,

Since RPG internally passes the parm as an address of the variable, is
there any performance advantage in passing the address of the variable as a
parm instead of the variable itself when the variable is large (say 2K).

Is the answer the same when calling a program vs a procedure in a Service
Program?

TIA
Vinay
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