dbs/mss/par_stmt_prepare is a SAP Parameter attribute which is used to control MSSQL: Prepare parameterized statements 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 .
When this parameter is turned off, DBSL will stop preparing SQL statements. This means the profiler trace will show sp_executesql instead of sp_prepexec or sp_prepare and then sp_execute. This will allow a clearer profiler trace because the statement text will always be visible.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.