rdisp/elem_per_queue is a SAP Parameter attribute which is used to control Number of Requests per Work Process 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 .
Parameter to determine the size of the internal request queue. The value
of this parameter is multiplied by the number of possible process type
(DIA, BTC, and so on). Currently there are 7 possible types (including
the outbound queue for SAP GUI output in the Dispatcher). That means,
that there is a maximum queue size of maximum 14000 savable requests for
the standard value 2000.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.