abap/shared_objects_size_MB is a SAP Parameter attribute which is used to control Size of Shared Objects Memory in MB information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
This parameter specifies the size of the memory area in which the ABAP
shared objects areas are created. This parmeter affects the memory
layout of the application server and cannot be dynamically changed.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.