JES2 allocates resources for BSC lines only when the lines are active. These resources can include a substantial amount of storage that is required by the processor control elements (PCEs) to support devices attached to RJE workstations.

A BSC dedicated line is non-shared if the SHARABLE=NO parameter is specified on the RMT(nnnn) initialization statement. However, setting SHARABLE=YES defines the line as capable of being shared; not that it is being shared, and when specified as SHARABLE=YES, the line will require sign on. If you enter a $D LINE command, a non-shared line displays RMTSHARE=NO and does not require sign on.

Dedicated lines that are non-shared do not require a /*SIGNON JES2 control statement to begin an RJE processing session. If you specify a /*SIGNON statement on a dedicated line, it is ignored because the workstation is considered active when the line is started. Note that lines are started by the central operator, who might not be aware of station use. Because specifying a /*SIGNON statement is a manual process at all RJE workstations, dedicating lines as non-shared conserves resources.

BSC lines that have been defined as dedicated can be sharable by specifying SHARABLE=YES on the RMT(nnnn) initialization statement, $T RMT(nnnn) command, or a $ADD RMT(nnnn) command. You can choose this option if you want to restrict particular lines to particular RJE workstations, but want the security provided by a /*SIGNON JES2 control statement.

Consider the following RJE workstation and line definitions to illustrate how RJE workstations can be defined as sharable or non-sharable, your use of a /*SIGNON statement, and how JES2 deals with conflicting shared line definitions:

 
      LINE(3)    UNIT=3099,...
⋮
      RMT(16)    LINE=3,SHARABLE=YES,...

Example 1 defines LINE3 and a single RJE workstation (RMT16) that will use that line. However, SHARABLE=YES indicates that if another RJE workstation also defines LINE3 it can do so. In any case, a /*SIGNON JES2 control statement is required.

 
      LINE(27)   UNIT=2799,...
⋮
      RMT(17)    LINE=27,SHARABLE=YES,...
      RMT(18)    LINE=27,SHARABLE=YES,...

Example 2 defines LINE27 and two RJE workstations (RMT17 and RMT18) that will use that line. However, if you mistakenly defined RMT17 by specifying SHARABLE=NO (with the intention of wanting it to share the line with RMT18), JES2 forces the RMT17 definition to SHARABLE=YES and you still obtain the result you want. Therefore, if two RMT(nnnn) statements specify the same line, the line is shared. To warn you of such an error, JES2 issues $HASP456 LINEnnnn REQUEST TO BE NON-SHARED BY REMOTE DENIED.

Now consider Example 3:

 
      LINE(27)   UNIT=2799,...
⋮
      RMT(17)    LINE=27,SHARABLE=YES,...
      RMT(18)    LINE=0,SHARABLE=YES,...

Although both RMT17 and RMT18 are defined as SHARABLE=YES, the RMT18 definition now specifies LINE=0 rather than LINE=27 as it did in Example 2. JES2 defines RMT18 as capable of using any nondedicated BSC line. A /*SIGNON JCL statement is required to start the RJE workstation. Although LINE27 is no longer shared, JES2 will indicate RMTSHARE=YES in response to a $D RMT17 command.

 
      LINE(27)   UNIT=2799,...
⋮
      RMT(16)    LINE=3,SHARABLE=YES,...
      RMT(17)    LINE=27,SHARABLE=NO,...
      RMT(18)    LINE=27,SHARABLE=NO,...

However, if you intended each RJE workstation (RMT17 and RMT18) to use a different line and mistakenly defined each to the same line (as shown in Example 4), JES2 forces both definitions to SHARABLE=YES and both RJE workstations use LINE27, different from your expectations and likely having availability implications. As in Example 2, JES2 issues $HASP456 LINEnnnn REQUEST TO BE NON-SHARED BY REMOTE DENIED to warn you of such an error.