1 08/22/83  External Storage
 2 
 3 External storage (PL/I external variables and FORTRAN common blocks)
 4 is usually allocated by the dynamic linker when a program is run.  The
 5 size and initial value is determined by information associated with
 6 the first procedure that references the storage.  If another procedure
 7 subsequently references the same storage, the linker ignores any
 8 associated initialization value.  If the size indicated is larger than
 9 that allocated, the linker signals linkage_error.  In this case, the
10 program cannot be restarted.
11 
12 
13 There are four ways of ensuring that the correct sizes and initial
14 values are allocated:
15 
16    1) Make all declarations for an external variable identical.
17       (Recommended)
18    2) Bind together all procedures that reference the same external
19       storage.
20    3) Use the set_fortran_common command before running the program,
21       giving it the names of all procedures containing relevant
22       information about external storage (largest sizes, correct
23       initial values, etc.) (Warning--continued operation with PL/I
24       procedures is not guaranteed).
25    4) Compile together all FORTRAN programs referencing the same common
26       blocks.  The list_external_variables command can be used to
27       display information about external variables or common blocks
28       already allocated.
29 
30 See allocation_storage.gi for general information on system storage
31 areas.