DFSFIXnn member of the IMS PROCLIB data set

Place control information in the IMS PROCLIB data set (typically named IMS.PROCLIB), as part of member DFSFIXnn, where nn is a two-character field supplied in the PARM field of the EXEC statement for the control region. See Environments that support IMS.SDFSRESL procedures.

If you are running XRF, you can define an additional DFSFIXnn member. This member is identified by the DEFERFIX=xx parameter in the DFSHSBxx member of the IMS PROCLIB data set and can contain only non-Fast Path page-fix options for the control region. In the active system, both page-fix lists are processed. In the alternate system, the page fix list specified by the DEFERFIX=xx parameter is not processed until takeover. This allows you to control how much page fixing takes place in the alternate system while it is in tracking mode.

Environments

This member can be used in the IMS DB/DC and DBCTL environments.

Syntax

Usage

The control information is contained in 80-character records. Continuation or sequencing must not be entered. In addition:

• Either commas or blanks can be used to separate parameters, except BLOCKS, POOLS, and NUC, which are followed by an equal (=) sign.
• The nnn subparameter of NUC= can be any one, two, or three-digit number from 1 to 100.
• Following the BLOCKS or POOLS parameters, either ALL or any subset of the list of blocks or pools, respectively, can be coded.
• Parameters (NUC, BLOCKS, POOLS, Modulename) can be entered in any order and can be repeated as desired. If NUC is repeated, the percentage specified on the last NUC= is used. If BLOCKS or POOLS is repeated, a block or pool is fixed if it is specified in any of the BLOCKS= or POOLS= specifications.
• The subparameters of blocks and pools can be specified in any order.
• Invalid parameters are ignored, an error message is issued, and scanning continues.
• An invalid format or an invalid word (one not beginning with an alphabetic character) causes all scanning to stop and an error message to be issued. No fixing is done.
• All 80 characters in each record are available for control information.
• The modulename must be specified as the full eight-character name of a loaded module.

Parameters

The parameters GLBP and LCLP can represent large amounts of storage. The terms GLBP and LCLP should not be interpreted as global and local storage, because the location of these pools can vary, based on whether the local storage option or the DL/I address space option is in effect. You should avoid using GLBP and LCLP; specify the pools to be fixed by name.

NUC=nnn

Is the percentage (specified by nnn) of the IMS load module (DFSVNUCx) to be page fixed.

If NUC=nnn is specified, a percentage of the nucleus, starting at location 0, is fixed regardless of what is placed there. IMS system definition places all the DC control blocks at the low end of the nucleus.

Modulename

The name of a loaded module. The specification of a module name does not cause that module to be fixed unless it has already been loaded into storage. (Module DFSVNUC0 cannot be fixed in this manner. See the NUC= keyword.)

If the DL/I address space option is being used, an attempt is made to fix a module in both the control and DL/I address spaces. If the module is loaded in only one of these address spaces, a message indicating that the module cannot be fixed is issued, in addition to the successful fix message.

Examples

The example in Example of DFSFIXnn causes:

• Module DFSDLR00 to be fixed
• 76% of the IMS nucleus to be fixed
• The control program nucleus blocks DC, SMB, PST, and SCD to be fixed
• The message format buffer pool to be fixed

The member specified in the EXEC PARM field is read and processed during the IMS initialization procedure.

A list of the fixed pages is maintained during the execution of IMS. When IMS terminates, this list is used to free the fixed pages before returning to z/OS.