rdisp/rfc_max_queue is a SAP Parameter attribute which is used to control Quota for dispatcher request queue 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 .
Quota for the maximum number of waiting requests in the dialog queue. If
this value is exceeded, no further resources are returned to the caller,
so that the server does not become overloaded. The value is given as a
percentage. In other words, it is dependent on the value currently set
in the profile. The parameter
See SAP Parameter Documentation for full SAP documentation for this profile parameter.