rsdb/esm/large_object_size is a SAP Parameter attribute which is used to control Expected size of the largest objects in ESM buffer 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 .
Estimate of the expected maximum size of the objects to be held in the
ESM buffer. The buffer can usually also store larger objects, however
the administration of larger objects affects the performance of the
See SAP Parameter Documentation for full SAP documentation for this profile parameter.