Re: CLLE optional parameters?

[Simon Coulter <shc@xxxxxxxxxxxxxxxxx>]

On 15/04/2009, at 12:47 AM, Vern Hamberg wrote:

> Now if anyone knows another way to avoid having to pass all parameters
> to a RTV* command - as IBM's work - let me know - other than  
> monitoring
> for MCH3601.

In CL you are stuck with the MONMSG MCH3601 method but in CLLE you can  
use the CEETSTA to check for existence and skip if not present.

> The documentation for this parameter of the PARM statement
> for commands says -
>
> "A CL variable name must be specified (on the CALL command) to receive
> the value."
>
> Not sure why it says "...the CALL command..."

Because the CALL command builds a parameter list from those specified.  
You can't specify an omitted or NULL value--help text expressly states  
that the *N placeholder won't work (although the help is wrong about  
not being able to pass a NULL value to a program**)--on the CALL  
command.

> but not to worry - it is
> assuming you have to pass all of the RTNVAL parameters, if specified.
> But the IBM commands don't behave that way, and checking MCH3601 takes
> care of it - until I find a better way.


On 540 with pointer support you can probably use the _NPMPARMLISTADDR  
built-in to check the number of parameters passed but since the  
Command Analyser will pass a *NULL pointer for unspecified return  
values the count will indicate all parameters were passed so you'll  
still have to check if you actually got a usable parameter.

David might be interested in that method for his optional parameter.  
In his situation he will not have anything passed so the count should  
reflect the actual number of parameters. CL gets operational  
descriptors passed so any of these methods should work reliably.

**The help text was accurate when it was written (S/38 days) because  
the available user languages did not support pointers so no NULL  
values could be passed.

Regards,
Simon Coulter.
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