Oracle scheduler max_jobs_Slave_processes is set to null, how many will be allocated? Executing the following query against my database:  

select value 
from dba_scheduler_global_attribute
where attribute_name='MAX_JOB_SLAVE_PROCESSES';


yields a value of NULL.  My question is what is the maximum number of slave processes that could be allocated, for job runs, when this value is set to null?
NULL implies no limits. Anything other than NULL sets a limit.

See the documentation here.