rdisp/jvm_max_no is a SAP Parameter attribute which is used to control 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 configures the maximum number of Java VMs that are to be
started on the VMC. If the parameter value is DEFAULT, then the value is
calculcated:
jvm_max_no = Total of parameter
See SAP Parameter Documentation for full SAP documentation for this profile parameter.