LA R1, PLIST SVC 202 DC AL4(ERRTN) PLIST DS OF DC CL8'DMSLADAD'
DC V (PAYDIRT)
DC F'O' Next, all payroll modules must have their absolute core-image files generated
and the payroll auxiliary directory must be initialized. In the example, the pay­
roll control module (PAYROLL) is given a mode number of 2 while the other
payroll modules are given a mode number of 1. When the PAYROLL program
is finally executed, only the files on the 194 disk with a mode number of 2 are
accessed. This means only the PAYROLL control program (which includes the
payroll auxiliary directory) will be referenced from the resident directory. All
the other payroll modules, because they have mode numbers of 1, are refer­
enced via the payroll auxiliary directory.
The following sequence of commands create the absolute core-image files for
the payroll modules and initialize the payroll auxiliary directory. ACCESS 194 A LOAD PAYROLL PAYDIRT GENMOD PAYROLL LOADMOD PAYROLL INCLUDE PAYROLL 1 GENMOD PAYROLL 1 LOADMOD PAYROLL INCLUDE PAYSHIFT GENMOD PAYSHIFT LOADMOD PAYROLL GENDIRT PAYDIRT Y
(now the auxiliary directory is included
in the payroll control module, but it is
not yet initialized.)
(this sequence of three commands is
repeated for each payroll module called
by PAYROLL.) GENMOD PAYROLL MODULE A2
When it is time to execute the PAYROLL program, the 194 disk must be
accessed as the Y-disk (the same mode letter as specified on the GENDIRT
command). Also, the 194 disk is accessed in a way that includes the PAY­ ROLL control program in the resident directory but not the other payroll mod­
ules. This is done by specifying a mode number of 2 on the ACCESS command. ACCESS 194 y/s * * Y2
Now, a request for a payroll module, such as PAYOVERT, can be successfully
fulfilled. The auxiliary directory will be searched and PAYOVERT will be
found on the Y -disk.
Note: A disk referred to by an auxiliary directory must be accessed as a
read-only disk.
Auxiliary Directories 461

Assembler Virtual Storage Requirements
Overlay Structures
Prestructured Overlay
462 VM/SP System Programmer's Guide
The minimum size virtual machine required by the assembler is 256K However, better performance is generally achieved if the assembler is run in 320K bytes of virtual storage. This size is recommended for medium and large
assemblies.
If more virtual storage is allocated to the assembler, the size of buffers and
work space can be increased. The amount of storage allocated to buffers and
work space determines assembler speed and capacity. Generally, as more stor­
age is allocated to work space, larger and more complex macro definitions can
be handled.
You can control the buffer sizes for the assembler utility data sets (SYSUTl, SYSUT2, and SYSUT3), and the size of the work space used during macro
processing, by specifying the BUFSIZE assembler option. Of the storage given,
the assembler first allocates storage for the ASSEMBLE and CMSLIB buffers
according to the specifications in the DD statements supplied by the FILEDEF
for the data sets. It then allocates storage for the modules of the assembler.
The remainder of the virtual machine is allocated to utility data set buffers and
macro generation dictionaries according to the BUFSIZE option specified: BUFSIZE(STD): 37 percent is allocated to buffers, and 63 percent to work space. This is the
default if you do not specify any BUFSIZE option. BUFSIZE(MIN) :
Each utility data set is allocated a single 790-byte buffer. The remaining
storage is allocated to work space. This allows relatively complex macro
definitions to be processed in a given virtual machine size, but the speed of
the assembly is substantially reduced.
An overlay structure can be created in CMS in two different ways, although CMS has no overlay supervision. For descriptions of all the CMS commands
mentioned, see the VM/SP CMS Command and Macro Reference.
A prestructured overlay program is created using the LOAD, INCLUDE, and GENMOD commands. Each overlay phase or segment is a nonrelocatable
core-image module created by GENMOD. The phases may be brought into
storage with the LOADMOD command.