Estimating Entire Net-Work Storage Requirements

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# 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

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

- Table 3: Special Storage Requirements of Line Drivers

## Table 1: Storage Areas Obtained from System

Storage Area | z/OS
--- | ---
Request queue: (NC parameter+1)*192 | AS(X)
Attached buffers: (NAB parameter*4112) | AS(X)
Entire Net-Work buffer pools* | Asynchronous buffers | AS(X)
Long-term buffers | AS
Short-term buffers | AS(X)
Page-fixed buffers | AS
Entire Net-Work trace table | AS(X)
Entire Net-Work control blocks | general | AS
Node | 48
Target | 32
Path | 32
CTCA DRIVER | 544
TCPI DRIVER | 4KB
TCPX DRIVER | 4KB
VTAM DRIVER | 4KB
XCF DRIVER | 2048
CTCA LINK | 992
TCPI LINK | 1KB
TCPX LINK | 1KB
VTAM LINK | 256
XCF LINK | 2048
ADAIOR data areas | general | AS
(for trace table, ECB list, etc.) | about 2KB

Abbreviation | Meaning
--- | ---
AS | from address space (private, below 16MB)
AS(X) | from address space (private, above 16MB)

## 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.

### On this page

- Table 1: Storage Areas Obtained from System
- Table 2: Storage Obtained from Entire Net-Work Buffer Pools
- Table 3: Special Storage Requirements of Line Drivers