DBCC CHECKDB ran out of memory
The statement "Since last month we had several occasions of DBCC CHECKDB crashing to this error..." makes me think that there was a change done on your system last month that may have caused this.  Was anything implemented last month to your knowledge?  For example any patches, updates to SQL Server, and applications were installed or upgraded on the SQL Server, etc...

Have you tried the below post to see if the issue is an OS Memory issue or if the error is caused by SQL?

https://social.msdn.microsoft.com/Forums/sqlserver/en-US/ff936d46-d210-4326-a112-0501a366ea41/dbcc-checkdb-failure-sql-2012-there-is-insufficient-system-memory-in-resource-pool-internal-to?forum=sqldatabaseengine

You could try to split out the DBCC CheckDB command to help alleviate any resource constraints.

Dividing DBCC CHECKDB over multiple days