I'm currently running El Capitan (10.11.6) on my Mac along with Creative Suite 6. Last month I constantly had the issue of my InDesign saying "out of memory" during my projects which resulted in me closing it. This doesn't happen as often anymore. Lately, I'm having issues with it crashing abruptly without an error code or message. I would say this has happened 17 times today over the course of 5 hours today especially.
If it helps my Mac specs are:
32 gb memory - 4 GHz processor - (Graphics) AMD Radeon R9 M395X 4096 MB
CS6 is unsupported under El Capitan and Sierra and will receive no updates to fix any incompatibilities. While someone may come along with something to help, be aware that there are countless threads here from people that were unable to get this combination to work in a satisfactory manner.
The only advice I have is to roll back to your earlier operating system or move to Creative Cloud.