vmcj/option/maxJavaHeap is a SAP Parameter attribute which is used to control max. java heap 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 .
Each virtual machine is mapped into a memory window. This memory
window is created dur-ing startup and has a fixed size. This size
determines how much memory a virtual machine can allocate for its
java heap.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.