How to work out how much space /opt/pb needs in MailStream Plus on UNIX/Linux

Operating System: UNIX and Linux
Per the UNIX Specialist-
It requires little space. Less than 10 megabytes. The only thing that will grow over time is the log file (/opt/pb/var/log) and only when a new or update install occurs. The /opt/pb area is only used for tracking installs and is used only during the install process for our products. 
Think of it like the Windows registry. 

However, if they choose to use this area to install the product into, then they will need appropriate space as per the product documentation. We recommend that this area NOT be used for product installs because it is typically on the root drive and may cause space issues during production runs.  
UPDATED:  August 8, 2017