PUMA concatenate fields

I am having memory issues when trying to concatenate two fields that will create a unique identifier for each PUMA across the US. How can I handle this memory allocation problem? thanks in advance

It sounds like your data file is too large for your system to process. I recommend selecting fewer samples, using the customize sample option to request a random subsample of your data, or using the select cases tool to request a subsample of your data that limit your file to records meeting specified criteria based on variables included in your extract.