rdisp/task_limit is a SAP Parameter attribute which is used to control Maximal request queue length per session 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 describes the number of open tasks that can exist for
each session. Tasks are created when RFC modules (CALL FUNCTION ...
STARTING NEW TASK ...) are called asynchronously and also when the HTTP
client interface is used. If the maximum number of open tasks is
exceeded, the processing is terminated and an ABAP short dump is
generated.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.