SSIS Memory allocation
SSIS runs outside of SQL Server's memory space so it's going to be contending with the memory allocated to the OS.

How much memory you allocate to SSIS is entirely dependent on how you define your SSIS packages. To go fast, which is what SSIS is designed for, it's going to push as much data into memory so that operations can be performed on it and slap it into the target system. You might only have 10GB of data from your source system but in theory you could consume more than 10GB of memory by using semi or fully blocking components as they will result in memory copies and such.