Recommended Procedures
If you want to update a VM/370 component, you should create your own
control file. This file should contain entries for your own updates as
well as for the IBM-supplied updates. Control File Preparation
Control files are used by the CMS UPDATE command. Both the VMFMAC and VMFASM update procedures invoke UPDATE with the CTL option to modify
source files. For VMFMAC and VMFASM, the control file must have a
filetype of CNTRL. In addition, the VMFLOAD program also uses a control
file: this is usually the same control file used by the VMFASM EXEC. For an understanding of how the update procedures work, you should
have a thorough understanding of the elements in a control file.
Control files are described extensively in the and the VM/J70 and The following
discussion summarizes how VMFMAC, VMFASM, and VMFLOAD use the control l*THIS IS A SAMPLE CNTRL FILE FOR LOCAL CP UPDATES TEXT MACS2 LOCALIB DMKMAC CMSLIB OSMACRO UP3 UPDTFIX 1. PTF5 FIXTEST LCL AUXLCL6 TEXT AUXRn0
7 IThis is a comment record. 2VMFASM uses the library list from the MACS record to issue a GLOBAL command before assembling the updated source file. The libraries are
searched in the order specified. DMKAMAC should precede DMKMAC if AP support is required. 3VMFASM and VMFLOAD use the update level identifier to identify the text
deck. VMFASM uses the update level identifier of the most recent
update that was found and applied to name the text deck produced by the
assembly. VMFLOAD uses update level identifiers to locate text decks
when punching a new CP, CMS, or RSCS nucleus.
The update level identifier on the MACS record is used by VMFASM to
name an assembled update text deck when no update files are found; it
is also used by VMFLOAD when it fails to locate a text file based on
update level identifiers associated with update files or auxiliary
control files . • The characters UPDT identify the filetype of a single update file, UPDTFIX 1 in this example. (The characters "UPDT" maybe omi tted.)
5The characters PTF in the update level identifier field identify this
file as a PTF file. FIXTEST is the filetype of the update file.
6The characters AUX identify an auxiliary control file that lists
additional updates to be applied, local modifications in this example. 7AUXRnO is the VM/370 auxiliary control file, listing updates
distributed by IBM. This file is listed at the bottom of the control
file so that these updates are applied first.
334 IBM VM/370 Planning and System Generation Guide

Recommended Procedures A control file can have any number of update identification (UPDTxxxx) records, AUX file identification (AUXxxxxx) records, and
comments, but can have only one MACS record. Example of a CP Update
Let's assume that you want to update CP, and then load a new CP nucleus.
The updates you are going to make consist of the following:
1. You want to add a command to CP. It has already been assembled
into the file DMKCMD TEXT. The CP module DMKCFC must be updated to
recognize the new command name, so you have updates to apply to
DMKCFC.
2. You have a local update to apply to the CP module DMKSCN. 3. You want to change two members of DM·KMAC MACLIB; you have updates
to apply to ACCTON COpy (for accounting routines) and to RDEVICE MACRO. Since the ACCTON COpy is modified, you have to reassemble DMKACO; changes to the RDEVICE macro require you to reassemble DMKRIO. The procedures that you would use to perform these updates are
described next. Remember that the same procedures can be used when you
apply updates to any of the VM/370 components.
Using VMFASM To Update Source Files If you are going to update a VM/370 module, you should always use the VMFASM EXEC procedure, since it allows you to incorporate IBM-supplied
updates with your own.
The files used in the following example are shown in Figure 36. In
addition to the 194, 294, and 191 minidisks, you should also have access
to the CP assembler language source files on MAINT 394, and the eMS system disk. The search order is:
191 A R/W 294 B/A RIO 194 CIA RIO 394 D/A RIO 190 S RIO This search order ensures that when the command
vmfasm dmkcfc yourown
is issued, the DMKCFC AUXLCL file from the 191 is used, not the copy on
the 294 disK. (The copy on the 191 contains an additional entry for the
second local update file, DMKCFC LOCAL02). The VMFASM EXEC prodecure invokes the UPDATE command with the CTL, STK, and PRINT options. In this example, UPDATE uses the file YOUROWN CNTRL to determine the order in which to apply the updates. Since the IBM auxiliary control file is the last item in YOUROWN CNTRL, updates
named in the file DMKCFC AUXRnO are applied first; then the entries
named in DMKCFC AUXLCL A are applied. Because no file named UPDTLCL exists, no update is applied for that entry in the control file. Part 5. Updating VM/370 335