modifyLayersByNameOnPage.js

var layerName = "Native/Bar/Nav",
	predicate = NSPredicate.predicateWithFormat("name == %@",layerName),
	layers = context.document.currentPage().children().filteredArrayUsingPredicate(predicate);

for (i = 0; i < layers.length; i++) {
	layers[i].setIsLocked(0);
	layers[i].frame().setHeight(42);
	layers[i].select_byExpandingSelection(true,false);
context.document.actionsController().actionForID("MSAlignLayersBottomAction").doPerformAction(nil);
	layers[i].setIsLocked(1);
	layers[i].select_byExpandingSelection(false,false);
}

context.document.showMessage(layers.length + " layer(s) have been modified");