Estimating Entire Net-Work Storage Requirements

Given the complexity of today's data processing environments, it is almost impossible to provide methods to predict the exact storage requirements of a software product.

The following tables provides rough estimates about the fixed storage requirements of Entire Net-Work and its various components, ignoring operating system-related storage requirements, which typically vary from installation to installation.

Table 1 contains the amounts of storage obtained from the operating system based on parameter specification or appropriate defaults. It does not include storage areas that are directly related to the operating system, such as operating system control blocks, I/O-related buffers, and control blocks (except where they are part of Entire Net-Work program modules or data areas).

Table 2 contains the amounts of storage obtained from the Entire Net-Work buffer pools by the control module and the various line drivers.

Table 3 contains special storage requirements of the line drivers (such as special common system storage areas) in the various operating system environments.


Table 1: Storage Areas Obtained from System

Storage Area Platform
z/OS VSE VM BS2000/OSD
Request queue:
(NC parameter+1)*192
AS(X) SYS/Part Virt.M Comm.Pool
Attached buffers:
(NAB parameter*4112)
AS(X) SYS/Part Virt.M Comm.Pool
Entire Net-Work buffer pools* Asynchronous buffers AS(X) Part Virt.M AS(X)
Long-term buffers AS Part Virt.M AS
Short-term buffers AS(X) Part Virt.M AS(X)
Page-fixed buffers AS Part Virt.M AS
Entire Net-Work trace table AS(X) Part Virt.M AS(X)
Entire Net-Work control blocks general AS Part Virt.M AS
Node 48 48 48 48
Target 32 32 32 32
Path 32 32 32 32
CTCA DRIVER 544 --- --- ---
DCAM DRIVER --- --- --- 848
IUCV DRIVER --- 4KB --- ---
TCPI DRIVER 4KB 4KB 4KB 4KB
TCPX DRIVER 4KB 4KB 4KB 4KB
VTAM DRIVER 4KB 4KB 4KB 4KB
XCF DRIVER 2048 --- --- ---
CTCA LINK 992 --- --- ---
DCAM LINK --- --- --- 56
IUCV LINK --- 168 168 168
TCPI LINK 1KB 1KB 1KB 1KB
TCPX LINK 1KB 1KB 1KB 1KB
VTAM LINK 256 256 256 256
XCF LINK 2048 --- --- ---
ADAIOR data areas general AS Part Virt.M AS
(for trace table, ECB list, etc.) about 2KB about 2KB about 2KB about 2KB
Abbreviation Meaning
AS from address space (private, below 16MB if XA or XS)
AS(X) from address space (private, above 16MB if XA or XS)

Table 2: Storage Obtained from Entire Net-Work Buffer Pools

Statistic Buffer Pool Types
Asynch Long-term Short-term Page-fixed
Segment size 64 64 512 2KB or 4KB
Control module buffer pool usage   UB MSG
RPLY
 
Queue manager buffer pool usage     BLK BLK
Abbreviation Meaning
BLK Storage for outgoing transmission blocks (after compression and blocking), from short-term pool or page-fixed pool, depending on line driver requirements. Storage requirements for one transmission block include, in addition to the messages contained, 48 bytes for a transmission block header.
MSG All messages sent or received; output messages kept until acknowledged by the access method, input messages kept until processed.
  The size of a message can be computed in the following way:
56 bytes for a message header
+ maxpath * 2 bytes for a node stack
+ 128 bytes for UB, ACB, etc.
+ size of FB, RB, SB, VB, IB to send or receive
RPLY A reply buffer for each user request for a target on this node if the information returned by the target will not fit into the original message buffer (that is, if a large record buffer or ISN buffer is to be returned to the user).
UB (only if 31-bit mode:) 64 bytes per user request for a target on this node, for the duration of the Adabas call.

Table 3: Special Storage Requirements of Line Drivers

Driver Special Storage Requirements

TCPX

NUMUSERS*256 is initially allocated from buffer pool storage for the Active Client Table (ACT). This value may dynamically expand if required.

Note:
In addition to the storage estimates shown in the table, approximately 250KB storage is required for executable code.