Provided by: systemtap-doc_2.3-1ubuntu1.4_all 

NAME
function::print_ubacktrace - Print stack back trace for current user-space task.
SYNOPSIS
print_ubacktrace()
ARGUMENTS
None
DESCRIPTION
Equivalent to print_ustack(ubacktrace), except that deeper stack nesting may be supported. Returns nothing. See print_backtrace for kernel backtrace.
NOTE
To get (full) backtraces for user space applications and shared shared libraries not mentioned in the current script run stap with -d /path/to/exe-or-so and/or add --ldd to load all needed unwind data.