MVS 3.8J

TSOKEY00 -- VTIOC parameters that are used by TSO/VTAM time sharing.

USERMAX=8,                       /* MAXIMUM USERS                    */
RECONLIM=60,                     /* MAXIMUM DISCONNECT MINUTES       */
BUFRSIZE=132,                    /* VTIOC BUFFER SIZE                */
HIBFREXT=13200,                  /* MAX BUFFERS BEFORE SWAP OUT      */
LOBFREXT=6600,                   /* MIMIMUM BUFFERS BEFORE SWAP IN   */
MODE=NOBREAK,                    /* KEYBOARD LOCK OPTION             */
CHNLEN=4,                        /* NO. OF RU'S PER CHAIN            */
SCRSIZE=1920                     /* MAXIMUM SCREEN SIZE              */

Parameter in IEASYSxx



  1. TSOKEY00 or an alternate member name may be specified by using the MEMBER operand or the keyword operand (overriding MBR) of the operator START command, or by coding it into the PARMLIB DD statement of the cataloged procedure evoked by the START command.


  • For each record, columns 1 through 71 are valid for data.

  • Data may be continued from one record to another by ending a record with a command and blank in contiguous data columns, then inserting data in any column of the data area on the next record.

  • A parameter must be complete in a record, it may not cross record boundaries, it may not be repeated.

  • A comma must seperate adjacent keywords.

  • Invalid or mispelled parameters are ignored and default values are substituted.


Parameter Meaning and Use Valid Range Default Value
USERMAX Specifies the maximum number of users that may be logged on to the TSO/VTAM time sharing system at one time.  (Note that because VTAM considers each user to be an application program, and because there must be an APPL definition statement that defines each application program to VTAM during VTAM network definition, this value may not exceed the number of APPL definition statements. 0 - maximum number of address spaces in the system 40
RECONLIM Specifies the time limit in minutes within which a user may reconnect after his line has been disconnected (that is, the amount of time an address space remains active in the event of terminal disconnection). 0 - 32,768 3
BUFRSIZE Specifies the size in bytes of a VTIOC buffer.  Input and output data smaller than the BUFRSIZE value uses cells equal to the BUFRSIZE value.  Input and output data larger than the BUFRSIZE value is assigned to dynamically allocated buffers (allocated by the GETMAIN macro) equal to the data size. 4 - 4092 132
HIBFREXT Specifies the maximum amount (in bytes) of virtual storage that can be dynamically allocated for output data.  When this value is reached, no more output requests are honored until LOBFREXT is reached.  (Input requests are rejected only when no virtual storage is available in the address space). Maximum size TPUT used at the installation - maximum amount of svilable virtual storage 48,000
LOBFREXT Specifies the minimum number of virtual storage bytes that can be dynamically allocated for output data.  When this value is reached, tasks that are suspended for lack of output buffers are marked as dispatchable. 0 - HIBFREXT-1 24,000
CHNLEN Specifies for output the number of request units (RUs) in each RU chain for IBM 3767 and IBM 3770 terminals.  This value determines the maximum size of a chain and, therefore, the maximum amount of data that can be sent to the terminal in one chain (CHNLEN x 256 = data transmitted).  This value also determines the maximum amount of data purged when the CANCEL key is pressed to stop printing of outbound (host-to-terminal) data.

The CHNLEN value is associated with the values specified on the PACING operand of the LU macro during network control program definition, and on the VPACING operand of the LU or PU macro during VTAM definition.  Use the CHNLEN default value (4) if the PACING and VPACING default values are used.  Otherwise, calculate CHNLEN by using the formula (2pn-2pm)+(2vn-2vm), where pn and pm are the PACING n and m values, and vn and vm are the VPACING values.  If more than one network control program is used with TSO/VTAM time sharing, the smallest value found when calculating the CHNLEN value should be used.  Otherwise, the network control program could enter slowdown mode.

1 - 10 4
SCRSIZE Specifies the default screen size of IBM 3270 systems network architecture (SNA) terminals: either 480 characters or 1920 characters.  (Use FEATUR2 operand of the LOCAL TERMINAL macros to specify non-SNA IBM 3270 screen sizes.)  This value affects only those terminals whose sizes were not specified by using the PSERVIC parameter of teh MODEENT macro during VTAM definition.

If an installation has IBM 3270 SNA terminals of only one screen size, SCRSIZE should specify that size.  If the installation has IBM 3270 SNA terminals of both screen sizes, SCRSIZE may be used to define the more common size, and the PSERVIC parameter may be used to define the less common size.

480 or 1920 480
ACBPW Specifies the optional password associated with all TSO/VTAM ACBs.  If a password is specified on the PRTCT parameter of VTAM's APPL definition statement, ACBPW must be specified. Any 1 to 8 EBCDIC characters None
MODE Specifies how 3276 and 3278 terminals are to be supported for TSO/VTAM.  BREAK indicates that the terminal keyboard is unlocked whenever possible and does not necessarily correspond to the issuance of a TGET.  NOBREAK indicates that the terminal keyboard is loked except when a TGET is issued.  The BREAKIN option of TPUT applies only when BREAK is specified. BREAK or NOBREAK NOBREAK
MODESW Specifies whether or not the TERMINAL command or the STBREAK macro can be used to change the mode of operation specified with the MODE parameter. YES or NO NO