Since HBOOK is an unchallenged standard, it was reasonable to build a certain amount of support directly into the DASH commands. Most importantly, you are provided a command to write the histograms out to a filename you specify on the command line. This can happen at the end of your job or between input files if that is useful to your analysis (the HIST/RESET command is probably helpful here).
You might decide to remake a histogram with different limits than those you put in your code. You can do this without recompiling and relinking using HIST/DELETE and HIST/HBOOK1, where the latter command respecifies that histogram.
Since one of the philosophical strengths of DASH is sharing modular code, DASH helps you manage histograms across modules. The command BOOK MYANA calls the book entrypoint for module MYANA and the histograms will be saved in the top level directory of the HBOOK output file (//PAWC). You may optionally specify a HBOOK subdirectory for a module: BOOK MYANA BANANA, which will put those histograms in //PAWC/BANANA. A convenient shortcut is to specify the optional second argument as ``*''. Then, BOOK MYANA * will use the modulename as the directory name and put the histograms in //PAWC/MYANA.
The way DASH manages histogram subdirectories is to call HCDIR before and after every entry into your module. Using histogram subdirectories helps avoid ID number conflicts as well as provides you with a simple heirarchy that makes browsing your histogram output file with PAW a little easier.