CSALIMIT start option

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Specifies the maximum amount of common service area (CSA) that can be used by VTAM®. This can be expressed as a number followed by a K (which represents 1024 bytes), or a number followed by an M (which represents 1048576 bytes). If you do not code M or K, K is assumed.

You can change the value of CSALIMIT with the MODIFY VTAMOPTS command or the MODIFY CSALIMIT command while VTAM is running. The F operand of this command allows you to force the value specified to be used as the CSA usage limit even though VTAM is currently using more CSA. If the operator forces a lower limit to take effect, the operator is prevented from using VTAM commands until the CSA usage falls below the specified limit, because CSA storage is needed to process all VTAM operator commands except HALT CANCEL. If the CSA usage does not fall below the specified CSA limit, VTAM must be canceled and restarted with a more appropriate CSALIMIT value specified.
  1. If the number you code is greater than the system CSA limit (all of CSA + ECSA defined in the system) CSALIMIT is set to 90% of the system CSA limit (which is the default). If the value specified is less than 25 MB and the ,F modifier is used on the command, a message will be issued. See the DISPLAY BFRUSE command in z/OS Communications Server: SNA Operation for information about displaying the current CSALIMIT setting, VTAM CSA usage, system CSA limit, and available system CSA storage.
  2. If CSALIMIT is specified (but without the ,F modifier) and VTAM CSA usage reaches this specified CSALIMIT value with 25% or more of system CSA storage remaining available for use, a warning message will be issued. VTAM will continue to execute until only 25% of CSA storage remains available for use. If you wish to prevent VTAM from using additional CSA beyond the specified CSALIMIT value, issue a MODIFY CSALIMIT or MODIFY VTAMOPTS,CSALIMIT command with the CSALIMIT value that you want and the ,F operand specified.
  3. If the CSA limit you code is reached and CSALIMIT=(value,F) was specified, errors are likely to occur. If LPBUF cannot be expanded, VTAM could enter an interlock condition. Therefore, if you code CSALIMIT, define LPBUF so that it does not have to expand. Other possible consequences are lost messages or failures when sessions are initiated or terminated.
  4. Specifying CSALIMIT does not affect the storage used by the communications storage manager (CSM).
Specifies that the maximum amount of CSA storage to be used by VTAM is 90% of the system CSA limit. See z/OS Communications Server: SNA Operation, DISPLAY BFRUSE, to find out what the system CSA limit is for your system.
Specifies the maximum amount of CSA storage to be used by VTAM. value can be specified in any of the following forms:
n is the number of 1024-byte increments that is the maximum amount of CSA that can be used by VTAM. The value of n is rounded up to the next multiple of 4.
q is the number of 1-megabyte increments that is the maximum amount of CSA that can be used by VTAM.
Forces the specified value, n, nK, or qM, to be used as the absolute CSA usage limit. If VTAM's CSA usage reaches this CSALIMIT value, all subsequent CSA requests by VTAM components are rejected until the current CSA value falls below the CSALIMIT value. If sufficient LFBUF storage is available, a modify CSALIMIT command can be used to increase the CSALIMIT value.

If the ,F is not specified, VTAM may use CSA until only 25% of system CSA storage remains available for use. If the ,F is specified, VTAM will not use more CSA than the CSALIMIT specified.