Getmain Help 
Author Message
 Getmain Help

How works exactly the getmain Macro?
--
PVB



Fri, 26 Mar 1999 03:00:00 GMT  
 Getmain Help

In many, many ways.

Generically, the GETMAIN macro provides an interface between an executing
program and the operating systems (PCP, MFT, MFT-II, MVT, ..... MVS/ESA).
This interface allows the operating system's storage management routines
to "dole out" currently unused storage to the program which issues the
GETMAIN macro (SVC usually).

Location of the storage (for XA and later operating systems) - above or
below the 16 MB line;  Subpool (a concept where storage has various
special attributes associated with it);  amount of storage; conditional or
unconditional; specified at compile time or specified at run time ....
all of these are specified in the GETMAIN invocation.

Typically the operating system will return an address, perhaps a length,
and a go / no go indication after the GETMAIN.

Hope this helps....

Rex Widmer
Builder of software archeology tools and other strange programs to help
survive in a legacy based world.



Sun, 28 Mar 1999 03:00:00 GMT  
 Getmain Help

: How works exactly the getmain Macro?
: --
: PVB

GETMAIN was the macro used on older (pre-ESA) versions of MVS for
dynamically obtaining areas virtual storage.  A related macro, FREEMAIN,
was used to free the acquired storage areas when no longer needed.

These macros were superseded in MVS/ESA by the STORAGE macro (although
GETMAIN and FREEMAIN are still supported, they don't work well for modern
programs that take advantage of S/390 cross-memory mode).

You should refer to 'MVS Assembler Services Guide', 'MVS Assembler
Services Reference', and 'MVS Extended Addressability Guide' for specifics
about the STORAGE macro and for a better general understanding of virtual
storage management under MVS.  For more in-depth, system-level treatments,
refer to 'MVS Authorized Assembler Services Guide' and 'MVS Authorized
Assembler Services Reference'.

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Mon, 29 Mar 1999 03:00:00 GMT  
 
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