While racesing is available in the single year 2013 and 2014 ACS, it is not yet available in the 2009-2013 and 2010-2014 five year ACS files. Someone in this forum raised this question, and the response was IPUMS staff was working to improve method of generating the racesing variable. Any update on the timing when racesing will be available in the latest five year ACS files
IPUMS-USA is currently evaluating different methods for generating these RACESING variables from multi-year ACS samples. Unfortunately I do not have more information regarding the expected release of these variables at this time. However, since the multi-year ACS samples are actually just an aggregation of single-year samples, all of which contain the RACESING variable, you could combine the single-year files to create a multi-year file from 2013 or 2014 with RACESING.
I hope this helps.