Max Jobs :
Max Jobs specifies the number of process instances that are kept in memory while executing. when it reaches to the limit (subject to flow limit) are paged out to disk.
Flow Limit :
Flow Limit specifies the maximum number of running process instances that are spawned before the process starter is suspended ie it enters a FLOW_CONTROLLED state and does not accept new events. This can be used to control the number of process instances running simultaneously and when the protocol generating the event can store the event till it is received, like email servers, JMS, RV etc. 0 specifies no limit and is the default.
Activation Limit :
Activation limit flag specifies that once a process instance is loaded and it must be placed in memory till it completes execution.
0,n and m are poissible values.. n is numeric value for Max Jobs and Flow Limit