The system parameters are stored in text files on the operating system level
in the global profile directory. Changes to profile parameters may not be done
in the text file directly, but only through a corresponding transaction within
SAP® [e.g. RZ10], otherwise the change history will not be complete.
Therefore and because of the risk of potential file violations the access
to these files needs to be restricted accordingly.

With the help of system parameters the system configuration is set up for
the runtime environment and various services e.g.
The corresponding directory path can be identified with the help of the
profile parameter DIR_PROFILE, where the different profile files are stored.
UNIX systems:/usr/sap/<SID>/SYS/pro

Windows NT: \\<SAPGLOBALHOST>\sapmnt\<SID>\sys\profile\

[where as <SID> represents the SAP system name and
<SAPGLOBALHOST> represents
the name of the  NT machine where the files are physically stored]

NOTE: Please be aware that the system parameters are case-sensitive.

A SAP® system has three different types of profiles:

DEFAULT.PFL – default profile
START_<instance> – start profile
<SID>_instance – instance profile

The general import and maintenance is done via transaction RZ10.
For the display of the transaction a corresponding application authorization
on S_RZL_ADM with activity 03 is required.
The maintenance authorization [ACTVT 01] needs to be strictly restricted
to members of the basis team only.

The sequence of profiles

The startup process is controlled by the start profile that is read by the start
program [sapstart]. Here the services [e.g. message, dialog, batch, gateway,
enqueue] are listed that are supposed to be started for the corresponding
instance. Therefore every instance has its own start profile.

An instance basically defines a group of resources such as memory and
processes in a logical unit within CCMS, and is also often described as
“server” or “application server”. A SAP® system can consist of one ore
more instances. Several instances can be installed at one
application server.

During start up, the system checks the parameter settings in the instance profile.
In case the parameter is not contained there, the system searches
the default profile. If no corresponding entry can be found,
the parameter will not be considered at all.

The default profile contains the parameter settings that are supposed
to be valid for all application servers.
The profile is unique and the name DEFAULT.PFL is obligatory.

Aside from the generally required instance parameters [e.g. memory control]
the instance profile completes the configuration set up as technical adjustment.

SAP@ provides approx 1.300 system parameters. These parameters are
grouped by categories.
The category login e.g. contains the relevant login parameters as for example
the parameter: login/password_expiration_time

The parameter name starts with the name of category.

An overview of the system parameters and their attributes can be gained
with the help of the table TPFYPROPTY [transaction SE16N e.g.].
represents the Quite a few parameters are configured based on the Boolean logic, where the 0NO and every value greater than 0 represents the YES.
Some of the parameters can be changed dynamically, others require a restart to become effective after change.

SAP® provides detailed documentation for most of the parameters.

Call transaction RZ11 end enter the name of the parameter you want
to get displayed.

Exhibit: RZ11

By pushing the button Documentation on the parameter display view,
you get the description displayed.

Exhibit: Detail view

Short overview of most common parameter categories:

apap            configuration of APAP/4® environment
auth             configuration of authorization environment
dbs              configuration of database environment
DIR              determination of directory path
structure for installation
em               configuration of extended memory
enqueue     configuration of enqueue processing
exe               SAP® program names
FN                determination of file names
[protected against customer change]
FT                determination of file specification
[protected against customer change]
gw                configuration of gateway environment
icm              configuration of internet communication
manager environment
j2ee             configuration of J2EE engine
login            configuration of login security
ms               configuration of message server
rdisp            configuration of dispatching environment
rsau             configuration of audit
rspo             configuration of spool environment
rslg              configuration of SysLog
rstr               configuration of system tracing
wdisp          configuration of web dispatching

The following reports and transactions allow the display of parameters as well.

Call transaction RSPFPAR or SE38 and enter RSPFPAR as program name.

You can search per exact name, category or with the help of wildcats.

In the column Name the customer specified entries will be displayed.
If the column is entry, the system default value will be taken.

SAP® already provides the following transactions with corresponding parameter pre-selection:

RSPFPAR                                   Display profile parameter
RSPFPAR_AUTH                      Authorization All
RSPFPAR_GATEWAY              SAP Gateway
RSPFPAR_LOGIN                    Logon Rules
RSPFPAR_PROFGEN             Profile Generator
RSPFPAR_RFC                        Remote Function Call
RSPFPAR_SAPSTAR              Hardcoded SAP*
RSPFPAR_SNC                       SNC
RSPFPAR_SPOOL                  Spool Parameters
RSPFPAR_STATISTICS          Workload Statistics
RSPFPAR_SYSLOG                Syslog Parameters
RSPFPAR_TABLEREC           Table Recording
RSPFPAR_TABLESTAT          Table Access Statistics

2. Report RSPARAM

Another report for the parameter display is the report RSPARAM via transaction
SE38 e.g..

The same logic as described above applies here also.
If no user-defined value is set, the system default value is valid.

Note: The unsubstituted value shows the set up before the substituted values
were replaced.

Per double-click onto a parameter name you can also branch to the parameter documentation in both reports. Select the   in the overview window.

In transaction AL11 the SAP® directories can be reviewed and accessed via continuous double-clicks [from parameter to file to file content].