In the user control code behing add an event handler to the CreatingDataSetRun event on the AxDataSource control

protected void Page_Init(object sender, EventArgs e)
{
this.AxDataSource1.CreatingDataSetRun += new EventHandler<CreatingDataSetRunEventArgs>(AxDataSource1_CreatingDataSetRun);
}

Set the param value  to the event arugments

void AxDataSource1_CreatingDataSetRun(object sender, CreatingDataSetRunEventArgs e)

{

e.DataSetRunArgs.parm = "4000";

}

 

In AOT override or add method in the data set and use element.args().parm() to received the paramter  

public void executeQuery()
{

 QueryBuildRange             custRange;
 ;
        custRange = SysQuery::findOrCreateRange(this.query().dataSourceNo(1), fieldnum(CustTable, AccountNum));
        custRange.value(element.args().parm());
   super();

}

You can also pass an Enum. For example

void AxDataSource1_CreatingDataSetRun(object sender, CreatingDataSetRunEventArgs e)
{
e.DataSetRunArgs.parmEnumType = EnumMetadata.EnumNum(this.AxSession, "EPFormAction");
e.DataSetRunArgs.parmEnum(2);
}

 

public void init()
{
    super();

     if (element.args().parmEnumType() == enumnum(EPFormAction) && element.args().parmEnum() == EPFormAction::CreateMode)
    {
        //do somethign here

    }
}