Create Mode Description (CRTMODD)

The Create Mode Description (CRTMODD) command creates a mode description for advanced-program-to-program communications (APPC) devices. A mode description defines the session characteristics and number of sessions for a link between the local and remote locations. More information on modes is in the APPC Programming book, SC41-5443 and the APPN Support information in the iSeries Information Center at http://www.iseries.ibm.com/infocenter.

APPC support uses Systems Network Architecture (SNA).

Parameters

Keyword	Description	Choices	Notes
MODD	Mode description	Communications name	Required, Positional 1
MAXSSN	Maximum sessions	1-512, 8	Optional
MAXCNV	Maximum conversations	1-512, 8	Optional
LCLCTLSSN	Locally controlled sessions	0-512, 4	Optional
PREESTSSN	Pre-established sessions	0-512, 0	Optional
MAXINPAC	Maximum inbound pacing value	1-32767, *CALC	Optional
INPACING	Inbound pacing value	0-63, 7	Optional
OUTPACING	Outbound pacing value	0-63, 7	Optional
MAXLENRU	Maximum length of request unit	241-32767, *CALC	Optional
DTACPR	Data compression	1-2147483647, NETATR, NONE, ALLOW, REQUEST, *REQUIRE	Optional
INDTACPR	Inbound data compression	RLE, LZ9, LZ10, LZ12, *NONE	Optional
OUTDTACPR	Outbound data compression	RLE, LZ9, LZ10, LZ12, *NONE	Optional
SLE	Session level encryption	NONE, ALL	Optional
TEXT	Text 'description'	Character value, *BLANK	Optional
COS	Class-of-service	Communications name, #CONNECT, #BATCH, #INTER, #BATCHSC, #INTERSC	Optional
AUT	Authority	Name, CHANGE, ALL, USE, EXCLUDE, *LIBCRTAUT	Optional

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Maximum sessions (MAXSSN)

Specifies the maximum number of active sessions that are established for this mode. This number must be greater than or equal to the sum of the number of locally controlled sessions as specified on the Locally controlled sessions prompt (LCLCTLSSN) and the number of locally controlled sessions specified at the remote location.

maximum-number-of-sessions: Specify the maximum number of sessions.
Valid values range from 1 to 512.

Maximum conversations (MAXCNV)

Specifies the maximum number of conversations that can be established at the same time with the remote system. The maximum number of conversations is the sum of synchronous and asynchronous conversations; this value must be greater than or equal to the value specified by the Maximum sessions prompt (MAXSSN parameter). A synchronous conversation is a conversation where both the source and the target programs are communicating. An asynchronous conversation is a conversation where the source program has detached itself from the conversation, but data is still being read by the target program.

maximum-number-of-conversations: Specify the maximum number of conversations. Valid values range from 1 to 512.

Pre-established sessions (PREESTSSN)

Specifies the maximum number of locally-controlled sessions that are established when the mode is started. Additional sessions are established as required, up to the maximum number of locally-controlled sessions specified in the Maximum sessions prompt (MAXSSN parameter). This value must be less than or equal to the value specified in the Locally controlled sessions prompt (LCLCTLSSN parameter).

number-of-established-sessions: Specify the maximum number of concurrent locally-controlled sessions established when the mode is started. Valid values range from 0 to 512.

Maximum inbound pacing value (MAXINPAC)

Specifies the maximum SNA pacing value used to schedule the incoming request units (RUs). Pacing is established by the receiving system to control the rate of transmission of the sending system to prevent loss of data.

Note: To ensure an optimum rate, the value *CALC is recommended.

*CALC: The system determines the value to use. The value is calculated to be 2*INPACING, which is two times the value specified on the INPACING parameter.
maximum-inbound-pacing: Specify a value, ranging from 1 through 32767 in RUs, for the maximum inbound pacing value.

Maximum length of request unit (MAXLENRU)

Specifies the maximum request unit (RU) length allowed.

Note: To ensure an optimum length, the value *CALC is recommended.

*CALC: The system calculates the value to use.

maximum-request-unit-length

Specify a value, ranging from 241 through 32767 in bytes, for the maximum length of incoming request units.

Some other common values are:

SDLC lines: 256, 512, 1024, 2048
Token-Ring Network lines: 256, 512, 1024, 1985
X.25 (QLLC) lines: 247, 503, 1015
X.25 (ELLC) lines: 241, 497, 1009

More information is in the Communications Configuration book, SC41-5401 book.

Data compression (DTACPR)

Specifies whether data compression is used.

*NETATR: The value from the DTACPR network attributes is used.
*NONE: Compression is not allowed on the session.
*ALLOW: Data compression is allowed on the session by the local system if requested by a remote system. The local system does not request compression.
If data compression is requested by the remote system, the data compression levels used by the session are the lower of the requested levels and the levels specified on the Inbound data compression and Outbound data compression prompts (INDTACPR and OUTDTACPR parameters).
*REQUEST: Data compression is requested on the session by the local system. However, the request can be refused or changed to lower compression levels by the remote system. Data compression is allowed on the session if requested by the remote system. The requested compression levels for inbound and outbound data are the levels specified on the Inbound data compression and Outbound data compression prompts (INDTACPR and OUTDTACPR parameters).
If data compression is requested by the remote system, the data compression levels used by the session are the lower of the requested levels and the levels specified on the Inbound data compression and Outbound data compression prompts (INDTACPR and OUTDTACPR parameters).
*REQUIRE: Data compression is required on the session. If the remote system does not accept the local system's exact required levels of compression, the session is not established.
The data compression levels that the local system require are the levels specified on the Inbound data compression and Outbound data compression prompts (INDTACPR and OUTDTACPR parameters).
line-speed: Specify the maximum line speed at which data is compressed. If the line speed of the link used by the session is less than or equal to this specified line speed, data compression is used for the session as if *REQUEST is specified. Otherwise, compression is used for the session as if *ALLOW is specified. Valid values range from 1 through 2147483647 in bits per second (bps).

Inbound data compression (INDTACPR)

Specifies the desired level of compression for inbound data. No data compression occurs if *NONE is specified on the Data compression prompt (DTACPR parameter).

Note: Adaptive dictionary-based compression is a dynamic compression algorithm, similar to Lempel-Ziv, that compresses previously seen strings to 9-, 10-, and 12-bit codes. This algorithm is referred to as LZ in the following parameters.

*RLE: The Run Length Encoding (RLE) algorithm is used. RLE substitutes a 1- or 2-byte sequence in the data stream for each repeated occurrence of the same character. This algorithm requires no storage and less processing time than the other options.

*LZ9: The LZ algorithm with the 9-bit code for repeated substrings in the data stream is used. These codes refer to entries in a common dictionary, created as the data flows between the sender and receiver. The LZ algorithms require storage and extra processing time. The LZ9 requires the least storage and processing time of the LZ algorithms; however, it compresses the data stream the least.

*LZ10: The LZ algorithm with the 10-bit code for repeated substrings in the data stream is used. These codes refer to entries in a common dictionary, created as the data flows between the sender and receiver. The LZ algorithms require storage and extra processing time. The LZ10 table algorithm requires more storage and processing time than the LZ9, but less than the LZ12. The LZ10 compresses the data stream more than the LZ9, but less than the LZ12.

*LZ12: The LZ algorithm with the 12-bit code for repeated substrings in the data stream is used. These codes refer to entries in a common dictionary, created as the data flows between the sender and receiver. The LZ algorithms require storage and extra processing time. LZ12 requires the most storage and processing time of the LZ algorithms; however, it compresses the data stream the most.

*NONE: No compression occurs.

Outbound data compression (OUTDTACPR)

Specifies the desired level of compression for outbound data. No data compression occurs if *NONE is specified on the Data compression prompt (DTACPR parameter).

*RLE: The Run Length Encoding (RLE) algorithm is used. RLE substitutes a 1- or 2-byte sequence in the data stream for each repeated occurrence of the same character. This algorithm requires no storage and less processing time than the other options.

*LZ9: The LZ algorithm with the 9-bit code for repeated substrings in the data stream is used. These codes refer to entries in a common dictionary, created as the data flows between the sender and receiver. The LZ algorithms require storage and extra processing time. The LZ9 requires the least storage and processing time of the LZ algorithms; however, it compresses the data stream the least.

*LZ10: The LZ algorithm with the 10-bit code for repeated substrings in the data stream is used. These codes refer to entries in a common dictionary, created as the data flows between the sender and receiver. The LZ algorithms require storage and extra processing time. The LZ10 table algorithm requires more storage and processing time than the LZ9, but less than the LZ12. The LZ10 compresses the data stream more than the LZ9, but less than the LZ12.

*LZ12: The LZ algorithm with the 12-bit code for repeated substrings in the data stream is used. These codes refer to entries in a common dictionary, created as the data flows between the sender and receiver. The LZ algorithms require storage and extra processing time. LZ12 requires the most storage and processing time of the LZ algorithms; however, it compresses the data stream the most.

*NONE: No compression occurs.

Session level encryption (SLE)

Specifies the desired level of session encryption.

*NONE: No data is encrypted or decrypted.
*ALL: All data is encrypted before it is sent out to the network and is decrypted as it is received from the network.
Note: The use of session level encryption requires that IBM Common Cryptographic Architecture Services for i5/OS is installed along with the Cryptographic Processor feature or the Cryptographic Processor-Commercial feature.

Authority (AUT)

Specifies the authority you are giving to users who do not have specific authority for the object, who are not on an authorization list, and whose group profile or supplemental group profiles do not have specific authority for the object.

*CHANGE: The user can perform all operations on the object except those limited to the owner or controlled by object existence (*OBJEXIST) and object management (*OBJMGT) authorities. The user can change and perform basic functions on the object. *CHANGE authority provides object operational (*OBJOPR) authority and all data authority. If the object is an authorization list, the user cannot add, change, or remove users.

*ALL: The user can perform all operations except those limited to the owner or controlled by authorization list management (*AUTLMGT) authority. The user can control the object's existence, specify the security for the object, change the object, and perform basic functions on the object. The user also can change ownership of the object.

*USE: The user can perform basic operations on the object, such as running a program or reading a file. The user cannot change the object. Use (*USE) authority provides object operational (*OBJOPR), read (*READ), and execute (*EXECUTE) authorities.

*EXCLUDE: The user cannot access the object.

*LIBCRTAUT: The system determines the authority for the object by using the value specified for the Create authority (CRTAUT) parameter on the Create Library (CRTLIB) command for the library containing the object to be created. If the value specified for the CRTAUT parameter is changed, the new value will not affect any existing objects.

name: Specify the name of an authorization list to be used for authority to the object. Users included in the authorization list are granted authority to the object as specified in the list. The authorization list must exist when the object is created.