slic/buffer_entries_dig_sig is a SAP Parameter attribute which is used to control Number of entries in buffer for digitally signed license keys 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 .
All valid digitally-signed license keys are read from the database when
starting the application server and stored in a buffer. This profile
parameter defines the size of the buffer.
If more license keys are found at the start then the value is
automatically increased. The parameter is therefore particularly useful
if further license keys are to be installed after the start of the
server. You cannot change the buffer size afterwards.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.