This option controls the 'Input dimension value' option in System Options:
In general all of the SetUserPreferenceXValue are controlling the System options and Document Properties. You can see the map here: 2013 SOLIDWORKS API Help - System Options and Document Properties
You need to set this particular option (i.e. swInputDimValOnCreate) to false if your macro updating the dimensions to avoid the popup which will block the operation cause macro will wait for user input for each changed dimension.