CHGSSNMAX (Change Session Maximum)

CHGSSNMAX Command syntax diagram

 

Purpose

The Change Session Maximum (CHGSSNMAX) command is used to dynamically change the maximum number of sessions the local location allows to an advanced program-to-program communications (APPC) mode. When a change to the MAXSSN parameter is made, the remote system is informed and allowed to negotiate for a lower session maximum. The remote system cannot negotiate a session maximum higher than the value specified for the local number of sessions specified. The resulting session maximum value is the current session maximum. Neither system may activate more sessions than the current session maximum. If the requested session maximum is accepted or negotiated by the remote system, the value requested on the CHGSSNMAX command is stored as the local session maximum; the remote system is not allowed to increase the current session maximum above the value stored as the local session maximum. This new value for the local session is only used the next time a new session maximum needs to be negotiated. The current session maximum, which controls how many sessions can be active between the local and remote location, is not changed if the command fails.

If the request to change the session maximum is rejected by the remote system, the CHGSSNMAX command ends abnormally and the local session maximum is changed as follows: If it is increasing, it is changed to the value specified; if it is decreasing, it is not changed.

This command is normally used by the system operator to control the number of sessions that can be active at the same time with a remote system. This command is used only when the remote location is active and the mode is in a started state. If the current number of active sessions is greater than the maximum number specified on the command, no new sessions are created until the number of active sessions falls below that specified on the command. If the current number of active sessions is less than the maximum number specified, sessions are not created until jobs requiring them are started.

The value created by the systems remains in effect until another CHGSSNMAX command or an End Mode (ENDMOD) command is run for the same mode, or until all the devices for the local location are varied off.

Many CHGSSNMAX commands can be sent before the maximum number of sessions is made active. The number specified the last time the command was called is the local session maximum value. If the device is varying off, this command ends with an error.

 

Notes

1. When this command is used to reduce the number of sessions with a remote system, the sessions that are ended first are the available locally controlled sessions, followed by any other available sessions. If the new session count is still not reached, other sessions are ended as jobs using them are completed or are canceled.
   
2. When the CHGSSNMAX command is used to increase the maximum number of sessions that can be created with a remote system, the locally controlled sessions are made available first (depending on the negotiated values), and then other sessions are made available.
   
3. The CHGSSNMAX command does not change the value specified for the MAXSSN parameter in the mode description; the Change Mode Description (CHGMODD) command must be used to permanently change the value. When the device is next varied on, the MAXSSN value from the mode description is used to limit the number of sessions instead of the MAXSSN value specified on a previous CHGSSNMAX command.

The APPC, APPN, and HPR topic in the Information Center has more information on this command.

 

Required Parameters

RMTLOCNAME

Specifies the name of the remote location that is used with this object.

MAXSSN

Specifies the number of sessions allowed with the remote system. This value represents the desired maximum session number for the specified mode name. It must be less than or equal to the MAXSSN parameter limit defined in the mode description. This value can be negotiated to a lower value by the remote system; therefore, the value specified here is not necessarily the value that is used. Valid values for this parameter are 1 through 512.

 

Optional Parameters

DEV

Specifies the name of the device description used with the remote location.

*LOC: The device associated with the remote location is used. If several devices are associated with the remote location, the system determines which device is used.

device-name: Specify the name of a communications device associated with the remote location. If the device name is not valid for the remote location, a message is sent when the program device entry is acquired. More information on device names is in APPC, APPN, and HPR topic in the Information Center.

MODE

Specifies the name of the mode that is changed. The mode name cannot be SNASVCMG or CPSVCMG; these mode names are reserved for system use.

*NETATR: The mode name specified in the network attributes is used.

*BLANK: The mode name consisting of 8 blank characters is used.

mode-name: Specify a value, no more than 8 characters, used to identify the mode that is changed.

LCLLOCNAME

Specifies the local location name.

*LOC: The device associated with the remote location is used. If several devices are associated with the remote location, the system determines which device is used.

*NETATR: The LCLLOCNAME value specified in the system network attributes is used.

local-location-name: Specify the local location name associated with the remote location.

RMTNETID

Specifies the remote network ID that is used with the remote location.

*LOC: The remote network identifier (ID) associated with the remote location is used. If several remote network IDs are associated with the remote location, the system determines which remote network ID is used.

*NETATR: The RMTNETID value specified in the system network attributes is used.

*NONE: No remote network identifier (ID) is used.

remote-network-ID: Specify a remote network ID for the remote location.

Example for CHGSSNMAX

CHGSSNMAX  RMTLOCNAME(APPCRLOC)  DEV(APPCDEV)
  MODE(APPC2)  MAXSSN(3)

This command changes the maximum number of sessions allowed by remote location APPCRLOC for mode APPC2 to a maximum of three.

Error messages for CHGSSNMAX

*ESCAPE Messages

CPF598B

The &1 command failed for one or more modes.