gtpi1m13System Installation Support Reference

Dynamic Load Module Environment Initialization (ISO-C)

User exit routine UCCCENV is used with ISO-C support. UCCCENV is activated when an ISO-C environment is initially created for a given ECB after all ISO-C control structures have been initialized, if the exit point named CENV is active. User exit CENV is called from an ISO-C environment. Exit point CENV is called from the dynamic load module (DLM) startup code (CSTRTD) of the CLMINT segment in the CIS0 library.

Some possible uses of this exit point include:

General Conditions at Entry

The registers at entry to UCCCENV are:

R5
0.

R8
Points to the DLM header.

R9
Address of the ECB.

R13-R15
See User Exit Routines - Common Entry Conditions.

The relevant ECB fields at entry to UCCCENV are:

CE2ISOC
Address of the Task Communication Area (TCA)

CE3SPTR
Address of the Data Save Area (DSA).

System Conditions at Entry

System state
Problem (see Programming Considerations at Entry, item 2)

System mask
Unmasked (see Programming Considerations at Entry, item 2)

Protect key
Working storage

Address state
EVM.

Programming Considerations at Entry

  1. The language work space (LWS) area cannot be incremented past the end of the stack (EOS) field in the task communication area (TCA).
  2. Usually, the system state, system mask, and protection key are as stated. However, there can be exceptions if system programs issued MONTC to get to supervisor state, changed the system mask, or changed the protection key.
  3. See User Exit Routines - Common Programming Considerations for other considerations.

Programming Considerations on Return

See User Exit Routines - Common Return Conditions.

General Conditions on Return

  1. If you need a locale that is different from the default locale, use R5 to indicate the locale. For EDCLOC-based locales, R5 must contain the name of the module that contains the locale. For localedef utility-based locales, R5 must contain the 4-character internal name of the locale.
  2. See User Exit Routines - Common Return Conditions.