Increase the reserved memory
You can use it if you want to sign large PDF files such as a 70 MB file, we will see how to reserve 1024 MB of memory because by default it reserves 512 MB and it is not enougth to sign those kind of documents.
On Windows
Go to \Program files\Isigma\ClickSign\ and edit the file ism.properties appending the property: java.memory.max=1024
On Linux
Edit the file $HOME/clicksign/menu/_run.sh and modify the property MAXHEAP setting the value 1024m