Editing DOS/360 and successors (section)

==Job control==

All DOS job control statements began with "{{mono|//}}" in card columns one and two except ''end-of-job'' which was "{{mono|/&␢}}", ''end-of-data'', "{{mono|/*␢}}", and ''comments'', "{{mono|*␢}}". (''In the description that follows the character "{{mono|␢}}" represents a single blank''.)
  
* The {{code|JOB}}  statement indicates "the beginning of control information for a job."  The format is <syntaxhighlight lang="jcl" inline>// JOB <jobname> <comments></syntaxhighlight>.  {{mono|<jobname>}} must be one to eight alphanumeric characters to identify the job.  {{mono|<comments>}} are ignored.
* The {{code|EXEC}}  statement identifies a program to be executed as a ''job step''.  "All control statements necessary for execution must be processed" before the {{code|EXEC}} statement is read.  The format is <syntaxhighlight lang="jcl" inline>// EXEC <program></syntaxhighlight>
* The {{code|PAUSE}}  statement "can be used to allow for operator action between job steps."  The format is <syntaxhighlight lang="jcl" inline>// PAUSE <comment></syntaxhighlight>.  The comment is used to provide a message to the operator.
* The {{code|comments}}  statement may be used to display a message to the operator.  The format is {{code|* <comment>}}.
* The ''end of data'' statement marks the end of data in the input stream.  The format is <syntaxhighlight lang="jcl" inline>/*</syntaxhighlight>.  Any data on the statement following the blank is ignored.
* The ''end of job'' statement marks the end of a job, and may indicate the end of data to be flushed if the job terminates abnormally.  The format is <syntaxhighlight lang="jcl" inline>/&</syntaxhighlight>.  Any data on the statement following the blank is ignored.
* The {{code|OPTION}}  statement specifies values of system options that apply to this job.  The format is <syntaxhighlight lang="jcl" inline>// OPTION <option1>[,<option2>...]</syntaxhighlight>.
* The {{code|ASSGN}}  statement "is used to assign a logical I/O unit to a physical device."  The format is <syntaxhighlight lang="jcl" inline>// ASSGN SYSxxx,<device>[,<tape option>]</syntaxhighlight>.  SYSxxx indicates a logical unit such as SYS001 or SYSIPT. {{mono|<device>}} is either "X'cuu'" to indicate a physical device (channel and unit), "IGN" for ignore, or "UA" for unassigned.  {{mono|<tape option>}} specifies either tape mode settings such as density, parity, etc., or "ALT" to indicate an alternate device.
* The {{code|RESET}}  statement resets specified I/O unit assignments to their permanent values.  The format is <syntaxhighlight lang="jcl" inline>// RESET <option></syntaxhighlight>.  {{mono|<option>}} may be "SYS" to reset all system logical unit assignments, "PROG" to reset all programmer assignments, "ALL" to reset all assignments, or "SYSxxx" to reset the assignment for the logical unit "SYSxxx", for example SYS002.
* The {{code|LISTIO}}  statement instructs the system to print a listing of all specified I/O assignments currently in effect.  The format is <syntaxhighlight lang="jcl" inline>// LISTIO <option></syntaxhighlight>.  {{mono|<option>}} is "SYS" to list all system assignments, "PROG", "F1", or "F2" to list all assignments for the background or specified foreground partition, "ALL", "SYSxxx", "X'cuu'", "UNITS" to list all assigned units, 'UA" to list all unassigned units, or "DOWN" to list all units marked as inoperative.
* The {{code|MTC}}  statement issues command to a magnetic tape unit.  The format is <syntaxhighlight lang="jcl" inline>// MTC <opcode>,SYSxxx[,<nn>]</syntaxhighlight>.  {{mono|<opcode>}} is a function such as "FSF" to forward space one file or "REW" to rewind the tape.  {{mono|<nn>}} is a number that can specify the number of times the operation is to be performed, such as forward space two files.
* The {{code|VOL}}  statement provides disk or tape volume label information for standard label checking.  The format is <syntaxhighlight lang="jcl" inline>// VOL SYSxxx,<volume></syntaxhighlight>.
* DOS originally provided the {{code|TPLAB}}  statement for tape label information and the {{code|DLAB}}  and {{code|XTENT}}  statements for disk label and extent information.  At least as early as 1968 the {{code|TPLAB}}  statement had been replaced by {{code|TLBL}}  and the {{code|DLAB}}  statement by {{code|DLBL}} .  These statements used numerous [[Job Control Language#Positional parameters|positional parameters]] and had fairly high information densities.
<ref name=ControlStatements>{{cite book|last=IBM Corporation|title=System/360 Disk Operating System User's Guide: Control Statement Techniques|year=1967|url=http://www.bitsavers.org/pdf/ibm/360/dos/GC20-1685-0_Disk_Operating_System_Users_Guide_Control_Statement_Techniques_Dec69.pdf}}</ref>