More Detail:::
What SUBMIT Does with Each LJL Statement:

For every statement, SUBMIT generates corresponding commands in the .deck file.
Below is a step-by-step breakdown:

One //jo line, as many /dd lines as are required, and as many //ex as are required

//jo sumjob owner=me@mail.com log=print class=a

• Generates a deck command to invoke ifclass a, which checks if the
  job's class allows execution at run time.
• Generates a deck command to Log "sumjob is starting" to /var/log/JCL/ with a timestamp.
• Generates a deck command to create /tmp/sumjob
• Generates a deck command to initializes /tmp/sumjob/jobname.log with a formatted header
  (e.g., via figlet sumjob).

Job Classes:
A = Runs as soon as submitted
B = Runs only if load is low enough
C = Runs in Off-Hours

//dd alias source(here|file=pathandfilename|new) disp(keep|scratch)

• Note the disp (disposition) if keep the put the file in /home/user/.lcl/jobname as whatever the alias is
  if the disp(scratch) then the file will go into the /tmp/jobname directory as named by the alias.
• Generate deck commands to

-- if source is here: copy lines from lcl up to '/*' to the deck file as a here document
if source is a file: add commands to copy the file into a working directory either in user's home
or in the tmp directory under the alias.
//dd users source(file=/etc/passwd) disp(keep) ==> copy /etc/passwd to /home/user/.ljl/users

//ex somecommand --options < alias

-Generate doc commands to execute the program as specified and save the output to the logfile
In this case echo (somecommand --options < aliasproperlyexpanded) > logfile

The deck file now forms a fully functional batch file to do the specified computation.