E – glossary entries

EAT
ECB activation table.
ECB
Entry control block.
ECB activation table (EAT)
The structure used by the E-type loader that keeps track of how many entry control blocks (ECBs) exist for each activation number.
ECB attribute
A setting that results in certain system actions to be taken when the ECB is processing.
ECB-controlled program
A program that requires an entry control block (ECB) for processing. It must be assigned a name; the BEGIN and FINIS macros must be the first and last source code statements, respectively.
A z/TPF program that is associated with the entry control block that it requires for execution. Also known as an E-type program.
ECB control table
The entry control block (ECB) control table keeps track of which ECBs are in use and the system virtual memory (SVM) address of each ECB.
ECB data levels
One of 16 pairs of data fields used by the entry control block (ECB) for input/output (I/O) or main storage block manipulation.
ECB heap
Contiguous blocks of ECB virtual memory (EVM) storage.
ECB heap buffer
A unit of storage that is allocated dynamically to an application from either the 31-bit or 64-bit ECB heap.
ECB heap trace
A trace facility that provides information about the latest entry control block (ECB) heap storage requests and releases for an ECB.
ECB origin
An identifier that is used with selective activate user exits that allows you to limit the use of an E-type loader loadset. This identifier can be a terminal address, communication line number, port number, user ID, network control program (NCP), adjacent link station (ALS), NCP name, and others.
ECB private area (EPA)
A segment of an address space that is allocated for the exclusive use of an entry control block (ECB) and its application set.
ECB register
The hardware register that contains the address of the entry control block (ECB) for an entry. By convention, the ECB register is register 9.
ECB resource monitor
A centralized facility that monitors the use of selected system resources on an entry control block (ECB) basis.
ECB trace
A trace facility that provides information about assembler macro calls, enter/back calls, and function calls to help you determine what the entry control block (ECB) was doing before a system error dump occurred.
ECB virtual address (EVA)
A location inside the virtual memory of an entry control block (ECB).
ECB virtual memory (EVM)
An address space that provides the only view of storage available to entry control block (ECB)-controlled programs. Each ECB runs in its own address space and has its own ECB virtual memory (EVM). Control program code may run in the EVM when acting for the ECB. (For example, enter/back is control program code that runs in the address space of the ECB.)
ECR
E-type loader control record.
ECT
ECB control table.
element
In z/TPF collection support (z/TPFCS), a subunit of a persistent collection. An element can consist of any data type, including binary strings and references to z/TPF files and other persistent collections.
A data object in an array.
In Extensible Markup Language (XML) an opening tag, a closing tag, and the contents between the two in an XML document. In the following example, there are three elements: name, first, and last: 
<name>
    <first>Mickey</first>
    <last>Mouse</last>
</name>
element equality
A state in which two elements are equal in length and equal in bit sequence for an entire collection.
ELF-compatible compiler
A compiler that is used on Linux®, but produces code in the executable and linking format (ELF).
ELT
E-type loader record table.
EMR
E-type loader main record.
emulator program processor
The processor in a loosely coupled complex that owns non-SNA lines.
encrypt
In symmetric cryptography, to systematically scramble information so that it cannot be read without knowing the coding key.
encryption
In computer security, the process of transforming data into an unintelligible form in such a way that the original data either cannot be obtained or can be obtained only by using a decryption process. See decryption.
encryption algorithm
An algorithm that scrambles the data so that it becomes unreadable to someone who intercepts it.
encryption key
A value used to encrypt data so that only possessors of the corresponding decryption key can decipher it.
end-of-message-complete (EOM)
The message delimiter that indicates that the last or only segment of data in a message has been received or sent. Synonymous with EOC.
end-of-message-incomplete (EOI)
The message delimiter that indicates that the message segment currently being sent or received is not the last.
end-of-message/pushbutton (EOP)
The message delimiter, sent from special terminals that have this end-of-message function key, that indicates that the message is complete.
end-of-unsolicited message (EOU)
The message delimiter that indicates that the last character of an unsolicited message has been received or sent.
endpoint group
A group of endpoints that maintain the same level of deployment for use with one or more rule applications.
enhanced logical record cache
A logical record cache that has a maximum entry size of greater than 4096 bytes. See also traditional logical record cache.
Enhanced queued direct I/O (EQDIO)
The link layer protocol that is used to communicate with the Network Express adapter. See also queued direct I/O (QDIO).
enter⁄back macros
Macros used to transfer control to other entry control block (ECB)-controlled programs.
enterprise name
The user-specified name of an enterprise or operations center that forms the first part of the system ID.
entry
The term used to refer to the entry control block (ECB) created for each input message and all the processing required by that message. Entries can also be created by programs using create-type macros.
entry control block (ECB)
A control block assigned to each input message/entry. It defines all resources allocated to process that entry and allows programs to be reentrant.
entry life
The amount of time an entry exists, measured from when the entry is made until its entry control block (ECB) is deleted.
entry point linkage table (EPLT)
A table that contains the addresses of the entry points internal to a program. Each program contains an entry point linkage table that, together with the procedure linkage table of a calling shared object, resolves calls from other programs.
environment block
In z/TPF collection support (z/TPFCS), a temporary block that is created and returned by the TO2_createEnv C function. A pointer to this block must be passed on every z/TPF collection support function call. The environment block specifies which data store and application to use to access collections.
EOC
End-of-message-complete. Synonym for EOM.
EOI
End-of-message-incomplete.
EOM
End-of-message-complete.
EOP
End-of-message⁄pushbutton.
EOU
End-of-unsolicited message.
EPA
ECB private area.
EPD
E-type loader program directory.
epilog
The code that gets executed each time a return from a function is processed. The epilog deallocates the storage allocated by the prolog, restores the calling program's registers, and returns to the calling function.
EPLT
Entry point linkage table.
epoch TOD clock
A format for the time-of-day (TOD) clock that is used to migrate to the extended TOD clock. An epoch TOD clock value is the upper 8 bytes of an extended TOD clock value and contains an epoch field. See also bracketed TOD clock and extended TOD clock.
EQDIO
Enhanced queued direct I/O.
equate macros
Declarative macros that assign values to system parameters during the assembly process.
ERA
Error recovery action.
ERD
E-type loader rules database.
error monitor mode
The condition that causes all errors that occur on a terminal interchange to be logged as they occur.
error recovery action (ERA) code
A code returned by a tape control unit describing the recommended error recovery action.
ETR
External time reference.
E-type loader
A program that loads E-type programs to the online z/TPF system. It consists of an offline load and an online load. Unlike the general file loader and the image loader, after you have programs loaded with the E-type loader you can begin using the newly loaded programs without IPLing the z/TPF system again. See also image loader, general file loader, and alternate face table (FCTB) loader.
E-type loader control record (ECR)
A processor-unique record containing the active loadsets for a processor.
E-type loader main record (EMR)
A structure that is a type of work list used to serialize and keep track of E-type loader operations. The EMR is also used as a communication vehicle between processors.
E-type loader program directory (EPD)
A structure used by the E-type loader that contains information about each program in a particular loadset.
E-type loader record table (ELT)
A structure that contains the ordinal number of each available #OLDx fixed file record that can be dispensed to the E-type loader.
E-type loader rules database (ERD)
A record that contains the default values for the E-type loader. These values can be altered to change the E-type loader for different environments.
E-type loader working record table (WRT)
A structure that resides in main storage and acts as a cache for the E-type loader #OLDx fixed file records that are being dispensed or returned.
E-type program
An entry control block (ECB)-controlled program.
EVA
ECB virtual address.
event facility
A method for entry control block (ECB)-controlled programs to define an event that can be waited for or posted by all ECBs knowing the name of the event.
event message business event
A type of business event that uses the event message format that is defined by the <esEventMessageFormat> element in the business event specification. An event message business event can be an event message data event or an event message signal event. See also business event, event message data event, and event message signal event.
event message data event
A type of data event that uses the event message format that is defined by the <esEventMessageFormat> element in the business event specification. See also data event and event message business event.
event message signal event
A type of signal event that uses the event message format that is defined by the <esEventMessageFormat> element in the business event specification. See also signal event and event message business event.
EVM
ECB virtual memory.
exclude
The process by which a program is marked as being excluded from an E-type loader loadset. This effectively removes the program from the loadset.
exclude function
The E-type loader function that removes 1 or more programs from a specified loadset.
executable script
In the z/TPF system, a type of executable file that can be used by the tpf_fork function to start a z/TPF application. An executable script is a file that contains readable text and statements that are interpreted. When the tpf_fork function is used to call an executable script, the first line of the executable script is parsed for the name of the z/TPF segment. The line must start with the #! characters, which is a UNIX shell convention. The access permission for the file must be set to execute. Internet servers typically use tpf_fork and executable scripts to run z/TPF applications.
exit vector
A user exit vector can consist of a SWISC expansion to an E-type program or an entry point address to a C-type program. User exit vectors are specified by multi-processor interconnect facility (MPIF) functions (such as IDENTIFY and CONNECT).
extended register save
A function that allows an application to specify at assembly time that general registers 10 - 13 (R10 - R13) will be saved across all control program general macros in addition to general registers R0 - R8.
extended resident
A description for a collection in which z/TPF collection support (z/TPFCS) stores data using an extended structure. See also extended structure.
extended structure
An object containing only control information and pointers that z/TPF collection support (z/TPFCS) uses to sort or retrieve the data elements that an application has stored in a collection. The data elements themselves are contained in pool file records that are chained to the extended structure. The DASDINDEXPool object of the StructureDasd class is just one example of several kinds of extended structures.
extended system work block (XWB)
A physical storage block that is protected and resides above 4 GB in memory. Extended system work blocks are not intended for use by applications. See also input/output block (IOB) and system work block (SWB).
extended TOD clock
A 16-byte format for the time-of-day (TOD) clock that is used to extend the time and date range of the standard z/TPF time-of-date (TOD) clock. This format contains an epoch field as its leftmost byte. See also bracketed TOD clock and epoch TOD clock.
external data definition
A definition appearing outside a function. The defined object is accessible to all functions that follow the definition and are located within the same source file as the definition.
external lock facility (XLF)
A facility that is used by the z/TPF system to synchronize updates to data records on a shared database. The XLF must be connected to and shared by all CPCs in a z/TPF loosely coupled complex. On the z/TPF system, you can use the multi-path lock facility (MPLF) hardware feature that is available for DASD control units or you can use one or more coupling facilities as XLFs with CF record lock support.
external time reference (ETR)
The synchronization of server time-of-day (TOD) clocks to ensure consistent time-stamp data across multiple servers and operating systems. External time reference (ETR) is a generic name for the IBM® Sysplex Timer. See also Sysplex Timer.
external time synchronization mechanism
A mechanism used to synchronize the time-of-day (TOD) clocks on different processors in a loosely coupled complex. The z/TPF system supports the Sysplex Timer or Server Time Protocol (STP) as the external time synchronization mechanism.